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Guideline           Ambient Air Quality Monitoring Network                       Recommendations and RulesContentChap. 1 -...
Chap. 4 - Calibration Laboratory      Calibration Laboratory      Receiving inspection, basic calibration, linearity tes...
Chap. 6 - Analytical Laboratory Air Quality      Inductive coupled mass spectroscopy (VARIAN ICP-MS 820)      Measuremen...
Guidelines for the Operation of the                      Air Quality Monitoring SystemContent1.   Introduction ..............
1. IntroductionThe following guidelines were drawn up within the framework of the followingtwinning-project:              ...
3. Tasks and Objectives of Air Quality MonitoringThe air quality monitoring tasks may be basically divided in:      Area-...
   Proof of calibration procedure traceability to National Standards.      Confirmation of professional competence throu...
     Guidance for air quality measurements by passive samplingThe steps in the quality assurance process are comprised in...
1. Structure of the Air Quality Monitoring Network                      Flow Chart of Assumptive StructuresNational       ...
2. Tasks description of the monitoring fieldsRegional Level:The monitoring network is headed by a scientist/academic, to w...
The monitoring network centre is headed by an academic and also comprises oneengineer and a technician. Their tasks are th...
Local Level:On this level, the „air quality‖ unit takes on the tasks of caring for the monitoringnetwork in the monitoring...
3. Quality Management in Air Quality MonitoringIt is stringent to establish a Quality Management System (QMS) for the air ...
3.1 Traceability of air quality dataThe regional calibration labs (RCL) have many diverse tasks. One of the main tasksis t...
characteristics are checked. The basic calibration and the first linearity test shall alsotake place in the framework of t...
3.4 Type approval test for suitability evaluation on siteThe European standards for the measurement procedures for SO 2, N...
Measurement Principles and Measurement MethodsContentMeasurement Principles and Measurement Methods .........................
Measurement methods for ambient air quality measurement are usually divided into- discontinuous methods and- continuous me...
2.1 Suitability TestsThe publication of suitable equipment for continuous ambient air qualitymeasurement by the BMU requir...
that the flow of both streams is kept constant. The influence of temperature on theconductivity must be compensated.2.3.2 ...
radiation absorption of these gases is high enough even in low concentrations inatmospheric air.The non-dispersive infrare...
the detector geometry. For continuous measurements the temperature and the massflow rate of the sample gas must be kept co...
2.3.8 Measurement with Beta-Ray AbsorptionIn dust measurement with beta-ray absorption systems, the sample air is suckedth...
6      Quality assurance7      Reports1      Problem analysisThe intention of the requirements described here is for the p...
how the problems presumably caused by air pollution in the area in question can bedescribed adequately and how they can be...
has already escaped into the atmosphere. Since effects are usually determined bythe mass of a substance absorbed, the dura...
2.2    Personnel planningPlanning of the personnel resources required to carry out the measurements shalldepend on the mea...
3      Measurement techniquesWith regard to the measuring procedures to be used, stipulations shall be laid downconcerning...
The time resolution of the measurements shall be in accordance with the air qualitycharacteristics to be determined. For c...
3.2    Performance characteristicsThe requirements for the performance characteristics of the measuring procedure tobe use...
-   Are the measuring procedures affected by the weather (temperature, humidity,    sunlight, frost), and is there a suita...
These points of infrastructure shall be taken into account when selecting themeasurement techniques.3.5    Data recording ...
spatial arrangement of the measuring points, the temporal distribution of sampling,the duration of individual measurements...
4.2     Measurement timesContinuous recordingContinuous recording of air quality characteristics is absolutely essential i...
is advisable likewise to target the selection of the measuring times, for example as afunction of the emission characteris...
If information is available concerning seasonal differences in the impact caused bythe types of air pollutants in question...
Measurement gapsThe proportion of measurement gaps shall be specified and reasons given in theevaluation. It may be necess...
OutliersThe treatment of outliers shall be specified and reasons given. The measured valuesdetermined as outliers shall be...
measurement uncertainty inherent in the measurement techniques is known. If it isonly a case of ensuring that the influenc...
6      Quality assuranceThe measurement plan should contain quality assurance (QA) statements. Themeasurement plan should ...
6 Evaluation6.1 Production of measured values6.2 Evaluation algorithms6.3 Measurement uncertainty6.4 Uncertainty of the re...
1 IntroductionAir pollution measurements are carried out to answer specific questions regarding specifiedair quality chara...
2.2 Classification of the objective2.2.1 Preliminary measurementsPreliminary measurements are measurements of air pollutan...
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
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Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
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Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
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Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
Guidelines for ambient air monitoring network
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Guidelines for ambient air monitoring network

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Guidelines for ambient air monitoring network

  1. 1. Guideline Ambient Air Quality Monitoring Network Recommendations and RulesContentChap. 1 - Introduction  Guidelines for the Operation of the Air Quality Monitoring System  Concept of the Air Quality Monitoring NetworkChap. 2 - Measurement Strategy  Measurement Principles and Measurement Methods  Planning of ambient air quality measurements - General rules  Planning of ambient air quality measurements – Rules for planning investigations of traffic related air pollutants in key pollution areas  Measurement Strategies for the Determination of Air Quality Characteristics in the Vicinity of Stationary Emission Sources  Handling of Measurement Uncertainty  Siting of Air Quality Monitoring StationsChap. 3 - Operation of the Monitoring Network  Measurement Procedures for the Determination of Particulate Matter Concentration and Gaseous Components  Monitoring network service  Performing of Maintenance/Maintenance Plans  Calibration of NO/NOx Analysers/Calibration Form  Calibration of SO2 Analysers/Calibration Form  Calibration of Ozone Analysers/Calibration Form  Calibration of CO Analysers/Calibration Form  Calibration of BTX Analysers/Calibration Form  Performing Repairs on Analysers/Repairs-Log  Change of Container Sites  Change of Measurement Location of Monitoring Vehicle (in German language) 1
  2. 2. Chap. 4 - Calibration Laboratory  Calibration Laboratory  Receiving inspection, basic calibration, linearity test and type approval test for suitability evaluation of measurement devices  Certification of test gases  Certification of test gas cylinders  Gravimetric Determination of PM10 Concentration by means of the High- Volume-Sampler DIGITEL DHA-80  Gravimetric Determination of PM2.5 Concentration by means of the High- Volume-Sampler DIGITEL DHA-80 (in German language)  Filter Handling (Cellulose Nitrate, Quartz Fibre) during the Determination of PM10 Concentration by means of DIGITEL DHA 80  Filter Preparation and Storage (Cellulose Nitrate, Quartz Fibre) for the Determination of PM10 Concentration by means of DIGITEL DHA 80  Balance Manual for the Verification of the Electronic Analytical Balance MC 210 P  Pipette Manual for the Verification of a Piston-Driven Air Displacement Pipette by means of an Analytical Balance  Calibration of the Reference Standard, Organisation and Deadlines  Determination of Uncertainty of Measurement for the Pollutant Nitrogen Dioxide (NO2) while employing a NO/NOx Chemiluminescence-MonitorChap. 5 - Network Data Centre  Recommendations on data validation in air quality monitoring networks  Recommendations on the calculation of aggregated data and statistical parameters  Automatic validation of air quality data  Information of the public on air quality  Control and release of air quality data / Forms daily/monthly/yearly validation  Reports, statements, publications  Handling of external requests on air quality data 2
  3. 3. Chap. 6 - Analytical Laboratory Air Quality  Inductive coupled mass spectroscopy (VARIAN ICP-MS 820)  Measurement of elements in dust and deposition dust  HPLC system Merck  Measurement of polycyclic aromatic hydrocarbons (PAH) in fine dust  Ion chromatograph Metrohm  Measurement of anions and cations in ambient air probes  Measurement of deposition dust and heavy metals content  Sampling of deposition dust  Digestion of dust and deposition dust for ICP-MS analysisChap. 7 – Air Quality Measurements by Passive Sampling  Air Quality Monitoring by Passive Sampling  The search for hot spots via passive sampler with respect to average NO2 exposure in an urban area  Evaluation of average benzene concentration by the use of passive samplers for the assessment of air quality according to EU Directive 2008/50/EC  Methods for measurement of Nitrogen Dioxide concentration in Ambient Air via Passive Sampler - Measurement method based on Saltzman Reaction  Determination of Benzene in ambient air via Passive Sampler 3
  4. 4. Guidelines for the Operation of the Air Quality Monitoring SystemContent1. Introduction ............................................................................................................ 52. Legal Framework ................................................................................................... 53. Tasks and Objectives of Air Quality Monitoring ............................................... 64. Quality Assurance ................................................................................................. 65. Organizational Foundations of the Guidelines ................................................. 76. Structure of the Guidelines for a Monitoring Network ..................................... 7 4
  5. 5. 1. IntroductionThe following guidelines were drawn up within the framework of the followingtwinning-project: Strengthening Administrative Capacities for Implementation of Air Quality Management SR 07 IB EN 01They describe the proposal of the twinning-experts with regard to the operation of thenetwork for air quality monitoring. They consist of recommendations, rules, standardoperation procedures (SOP) and should be used as a guidance for the operation ofair quality monitoring networks. 2. Legal FrameworkThe guidelines refer to the monitoring of air pollutants in the ambient air. The mainlegal foundation in this regard in Europe are the CAFE-Directive 2008/50/EC and the4th Daughter Directive 2004/107/EC of the Commission of the European Community,which set limit values and guide values for each air pollutant. The Europeandirectives with their mandatory implementation in the member states have led tosignificant development on the legislative level but also to important technical andanalytical progress. The following criteria are to be mentioned as main focus:  Significantly severer limit values by implementation of the effect-oriented standards of the World Health Organisation WHO  Extensive measures plans and action plans for the improvement of air quality  Extensive information of the public  Significantly higher demands with regard to the quality of air quality data and to the quality management systems of the monitoring networks (Data Quality Objectives of the EU Directives) 5
  6. 6. 3. Tasks and Objectives of Air Quality MonitoringThe air quality monitoring tasks may be basically divided in:  Area-oriented measurements: determination of the overall exposure to air pollutants in different areas and its influence upon the population living there, upon the vegetation and upon assets.  Local-oriented measurements: determination of specific exposure to air pollutants in places with unusually high emissions and the sometimes limit- value-exceeding levels of air pollutants deriving from it. (e.g. highly frequented urban canyons)  Facility-oriented measurements: determination of specific pollution produced by air pollutants from one or more industrial emitters.The specific objectives of air quality monitoring according to EU Directives are thefollowing:  To verify whether the limit values and guide values set in the EU Directives are being observed.  The analysis of reasons for high air pollution.  To control the effectiveness of the measures taken for air quality improvement.  To verify Dispersion Modelling for pollutants in the ambient air.  To determine temporal trends with regard to air pollutant levels.  To investigate long range transport of air pollutants. 4. Quality AssuranceAs a rule, the metrological air quality verification is regulated by state provisions,which mainly rely on European Directives, and takes place according to state-acknowledged standards and guidelines. Reference to this will be made in someinstances in the present guidelines. The quality assurance measures for theinvestigation of air quality refer to the following levels of action:  Specifications with regard to the monitoring strategy i.e. definition of task, choice of monitoring location, monitoring period, etc.  The use of verified monitoring equipment, the use of reference and equivalence procedures. 6
  7. 7.  Proof of calibration procedure traceability to National Standards.  Confirmation of professional competence through accreditation of laboratories and monitoring networks by an accreditation body with European recognition  Quality control of monitoring stations and networks by means of national and international interlaboratory tests, audits and quality management systemsThe guidelines provide valuable support for many of these points, in order to reachquality targets and to be able to provide the European Commission with reliable dataon air quality. 5. Organizational Foundations of the GuidelinesThe guidelines mainly refer to European EN standards and Directives, that will not bedetailed here, but that will be referred to in particular cases. There will also bereference to the operating instructions of the individual devices of the monitoringnetwork.In the SOPs the operation of regional monitoring networks will be taken as a basis.The national level will only be referred to. This means that neither the function of theNational Data Centre (for the provision of EoI requirements) nor that of the NationalReference Laboratory will be described. 6. Structure of the Guidelines for a Monitoring NetworkThe guidelines comprise all important tasks which belong to the operation of airquality monitoring networks according to the EU Directives for air quality:  Guidelines for the measurement strategy of air quality  Regulations for the operation of the monitoring network  Regulations for the work of the calibration laboratory  Regulations for the network data centre with regard to data collection, the database for measured values, the data validation steps and several aspects on reporting.  Guidelines for important tasks of the analytical laboratory air quality 7
  8. 8.  Guidance for air quality measurements by passive samplingThe steps in the quality assurance process are comprised in the guidelines foroperation and maintenance of the stations, as well as in the European standards theyhave been based upon.The guidelines can be divided as follows:  Structure of the air quality monitoring system  Guidelines measurement strategy  Guidelines concerning the operation tasks of the monitoring network  Guidelines concerning the tasks of the calibration laboratory  Guidelines concerning the tasks of the network data centre  Guidelines concerning the tasks of the analytical laboratory air quality  Guidelines concerning air quality measurements by passive samplingA complete list of all documents included in this Guideline ―Ambient Air QualityMonitoring Network‖ is given in the content. Concept of the Air Quality Monitoring NetworkContent1. Structure of the Air Quality Monitoring Network ............................................ 92. Tasks description of the monitoring fields ................................................... 103. Quality Management in Air Quality Monitoring ............................................. 13 3.1 Traceability of air quality data ..................................................................... 14 3.2 Linearity test ............................................................................................... 14 3.3 Receiving inspection .................................................................................. 14 3.4 Type approval test for suitability evaluation on site .................................... 16 3.5 Reference standards for physical measures .............................................. 16 3.6 Gravimetric analysis ................................................................................... 16 8
  9. 9. 1. Structure of the Air Quality Monitoring Network Flow Chart of Assumptive StructuresNational National National Data Modelling .........Level Reference Centre: EU- Laboratory Reporting, national informationRegionalLevel Monitoring Network 1/0/1* * = No. Acad./Eng./Techn. Monitoring network Calibration lab and Monitoring network centre service analytical lab 1/1/4 1/3/3 1/1/1 Maintenance Test gases bottles Data control and Test gases release Repairs Transfer standards Validation Gravimetric Calculation of Calibration analysis statistical parameters Evaluation of Data Analysis and measurement Assessment devices Reporting Balance manual Data dissemination Information of the publicLocalLevel Station operation: Fault-clearance service Maintenance work Security aspects Information of the population 9
  10. 10. 2. Tasks description of the monitoring fieldsRegional Level:The monitoring network is headed by a scientist/academic, to whom an assistant isassigned.The monitoring network service is led by an academic and also comprises oneengineer and 4 technicians. Their tasks are the following:Task description:Academic Managing, monitoring strategy, personnel management and budgetEngineer Start-up verifications Adaptation of new devices to the monitoring network Training of technicians Procurement (devices, spare and consumable material) Location planning and arrangement Responsible for transfer standards and their verification in the calibration lab Control of completed calibrationsTechnician Maintenance and repairs Calibrations According to qualification divided into maintenance technician and repair technician.The Laboratory belonging to the monitoring network is composed of the two units: - Calibration lab - Analytical lab for inorganic and organic air pollutantsThe laboratory is led by an academic. He has three subordinate engineers with thefollowing assignments: - Calibration lab (reference equipment for SO2, NO, NO2, O3, CO, benzene, particles; gravimetric analysis PM10 and PM2,5; transfer standards; calibrations and linearity verifications for new and repaired equipment - Analytical lab for inorganic air pollutant components: Pb, Cd, Ni, As, Hg and other heavy metals; inorganic components in dust and deposit. - Analytical lab for organic air pollutant components: BTX, PAH, Benzo(a)Pyrene, rust; if necessary: Furan, DioxinTask description:Calibration lab engineer Chemistry, physics, electronicsEngineer Analytical lab/inorg. Focus on inorg. chemistry, AAS, ICP/MSEngineer analytical lab/org. Focus on org. chemistry, GC, HPLCGeneral: quality management, determination of measurement uncertainty, proceduredevelopment, participation in interlaboratory tests, laboratory comparisons. 10
  11. 11. The monitoring network centre is headed by an academic and also comprises oneengineer and a technician. Their tasks are the following:Task description:Academic Management of the data centre Planning/further development of database and data communication Further development of data validation procedures ReportingEngineer Administration of network of monitoring network Data validation Data assessment Preparation work for reporting Data dissemination according to requirements (EU-requirements, requests from municipalities, research, media)Technician Computer maintenance, data transfers, database, support with data validation, assessment, reporting 11
  12. 12. Local Level:On this level, the „air quality‖ unit takes on the tasks of caring for the monitoringnetwork in the monitoring department. This unit is led by an engineer, who mainlyorganizes the support for stations and takes on the data assessment on local level aswell as information of the local public. He is accompanied by 1-2 technicians who areresponsible for fault clearance, maintenance work and the overall operation of thestations. The number of necessary employees depends on the number of theattended stations; as indicative number one technician can be calculated for everythree stations.Task description:Engineer Organization of monitoring station Data assessment/ collaboration in Clear Air Plans and action plans Information of the local public, municipalities, businesses, media, schools, action groups, etc. Support of monitoring network service in special investigations (e.g. in the framework of approval procedures, road planning, specific land-use areas, industrial parks, regional planning procedures) Special programmes for the determination of PM-10 pollutionTechnician Maintenance: exchange of all consumable material Repairs: exchange of worn out pieces (Pumps, membranes, magnet valves). First fault diagnosis until the decision is taken, whether the devices needs to be exchanged. Support with Public RelationsThe tasks of the regional and local levels need to be defined very accurately.Experience has shown that otherwise responsibility in case of malfunctions iscritically. 12
  13. 13. 3. Quality Management in Air Quality MonitoringIt is stringent to establish a Quality Management System (QMS) for the air qualitymonitoring. This system must comply with EU regulations and must be implementedat the same time with the installation of the air quality monitoring networks.For each air quality monitoring network, the QMS is vital, because very importantdecisions regarding air quality monitoring, legislation against emission sourceoperators depend totally or partially on the measurement data. Not only are incorrectdata and false information useless, but they can lead to wrong decisions andendanger human health. The QMS should comprise the following elements:  Selection of measurement locations  Selection of measurement devices used  Calibration of measurement devices (monitors)  Maintenance of monitors and monitoring stations  Management of measurement data  Validation of measurement dataA good data quality and a high data capture rate are essential in an air qualitymonitoring network in order to reach the Data Quality Objectives (DQO) of the EUDirectives. In order to ensure that the data are sufficiently accurate, reliable andcomparable to other monitoring networks, the measures for quality managementhave to be consistently used in the entire network.The QM-System has the following fundamental objectives:  The measurement data of the network must be representative for existing air pollutions in the monitored (urban) area.  The measurement must be accurate, precise and traceable.  The measurement data must be comparable and reproducible: the results of a geographically extended area must be consistent and comparable to international standards.  The measurement results over the entire period of the monitoring network operation must be consistent (consistent over time).The basics for the measurement are the primary and secondary standards, which areusually cared for by the National Reference Laboratory (NRL). Additionally, there arethe necessary absolute or traceable metrological standards, for which the NationalMetrological Institute is responsible (temperature, pressure, flow rate, weight, etc).The necessary requirements for the achievement of uniformity are:  The used measurement methods must be known (known performance) and their scope must be defined.  Each calibration must be traceable by means of an uninterrupted string to international standards.  The measurements must be performed within a documented QMS.Because of the importance of these general requirements for the measurements inan air quality monitoring network, the main tasks of the regional calibrationlaboratories (RCL) are described in more detail in the next pages. 13
  14. 14. 3.1 Traceability of air quality dataThe regional calibration labs (RCL) have many diverse tasks. One of the main tasksis the supply of traceable transfer standards for the calibration of measurementdevices in the monitoring networks.Traceable means, that these transfer standards are connected tonational/international standards by an uninterrupted chain of comparisonmeasurements with known measurement uncertainty.National standards shall be kept by the National Reference Laboratory (NRL) andshall be linked to international standards by means of international comparisonmeasurements.The laboratory reference standards used in the calibration labs as a basis forcalibration have to be certified by the NRL by means of comparison measurementswith the national standards. The uncertainty of the certified test gas concentrationshall always be indicated in this process.Both test gases in test gas bottles and test gas generators can be used as laboratoryreference standards. The stability of the laboratory reference standards used must bemonitored constantly by the Reference Calibration Labs by means of appropriatemeasures (e.g. cross-checks with a second standard or independent procedures).The calibration labs perform comparison measurements of the transfer standardswith the laboratory reference standards and determine their uncertainty. To thispurpose, reference measurement devices are used, which have been previouslycalibrated with the laboratory reference standards. Then, the transfer standards aredeployed in the monitoring stations for the calibration of measurement devices. Thus,the traceability of air quality data to national standards is guaranteed.Additional to reference standards, the RCL‘s also have other standards at theirdisposal (laboratory work standards), which can be used, for example for the dailyzero/span control of the reference measurement devices and for the linearity test ofmeasurement devices. 3.2 Linearity testThe linearity of measurement devices is to be tested regularly, yearly or every threeyears, according to test results. Also, after repairs or basic maintenance works onmeasurement devices, a new linearity test shall be necessary.With newly procured measurement devices the linearity test shall take place in theRCL before its installation in a monitoring station. 3.3 Receiving inspectionThe EN ISO/IEC 17025 „General requirements for the competence of testing andcalibration laboratories― requires that newly acquired measurement devices aretested for the observance of technical specifications and for compliance with therequirements of that particular measurement procedure. These receiving inspectionsshall take place in the RCL.The receiving inspection for new measurement devices comprises a formal part, inwhich the completeness of delivery is checked and a practical part, in which datatransfer, device parameterisation and the compliance with special performance 14
  15. 15. characteristics are checked. The basic calibration and the first linearity test shall alsotake place in the framework of the receiving inspection. Only if the measurementdevice fulfils all requirements it may be cleared for measurement use.The results of the inspection and the approval of measurement devices are to bedocumented.The following scheme shall again make clear the tasks described above: National Standards (NRL) measurements comparison certification calibration measurement Laboratory Reference Reference Analyser Transfer Standards Standards certification zero/span check basic calibration Laboratory Working Standards calibration Lack of Fit check initial checks Analyser 15
  16. 16. 3.4 Type approval test for suitability evaluation on siteThe European standards for the measurement procedures for SO 2, NO/NO2, O3 andCO require that before use a measurement device be tested for its suitability to fulfilthe requirements of EU Directives regarding data quality even in the specificconditions of the envisaged measurement site. For this, the measurement uncertaintyof the measurement device is calculated taking into consideration the results of thetype approval test and the specific conditions of the measurement site and thencompared with the requirements regarding measurement uncertainty of the EUDirectives.The task of performing the type approval test for suitability evaluation shall be fulfilledin the RCL‘s. A close collaboration between calibration lab, monitoring networkservice and monitoring network centre shall be necessary in order to determine thestarting values required for the calculation of measurement uncertainty.All calculations shall be documented 3.5 Reference standards for physical measuresIn the monitoring network service volume flows, from PM10 samplers for instance, aswell as pressure and temperature sensors have to be verified regularly.The balances used for the gravimetric determination of PM10 shall be calibratedregularly with reference weights.The RCL‘s must have at their disposal calibration reference measurement devicesand certified reference weights for the measures volume flow, pressure, temperatureand mass and must organise and ensure their regular recalibration or metrologicalverification by the NMI.These reference measurement devices shall be used in order to calibrate themeasurement devices used for the tests in the stations and the balances. 3.6 Gravimetric analysisThe RCL‘s are responsible for the gravimetric determination of PM10 and PM2,5. Forthis, they have air conditioned balance rooms for filter conditioning and weighting.The course of action and the requirements for the gravimetric determination of PM10and PM2,5 are described in the corresponding European standards (EN 12341 andEN 14907). 16
  17. 17. Measurement Principles and Measurement MethodsContentMeasurement Principles and Measurement Methods .............................................. 171. Discontinuous methods .......................................................................................... 182. Continuous Measurements ..................................................................................... 18 2.1 Suitability Tests .................................................................................................... 19 2.2 Description of Continuous Ambient Air Measurement Equipment ........................ 19 2.3 Measurement Principles ....................................................................................... 19 2.3.1 Conductometry ............................................................................................... 19 2.3.2 Chemiluminescence Measurement................................................................. 20 2.3.3 UV Fluorescence Measurement ..................................................................... 20 2.3.4 Measurement of UV Absorption ...................................................................... 21 2.3.5 Flame lonisation Measurement ....................................................................... 21 2.3.6 Optical Long-Path Monitoring (Path-Integrating Measurement) ...................... 22 2.3.7 Automated Gas Chromatography ................................................................... 22 2.3.8 Measurement with Beta-Ray Absorption ........................................................ 23 17
  18. 18. Measurement methods for ambient air quality measurement are usually divided into- discontinuous methods and- continuous methods.1. Discontinuous methodsDiscontinuous methods are mostly manual methods for which sampling on site andanalysis in the laboratory are two separate steps. Continuous methods typicallyinvolve automatic equipment at a fixed site to carry out both sampling and analysis.However, these distinctions do not quite take account of the great variety of airquality measurement methods. "Discontinuous" measurements can be carried outwith automatic equipment at the sampling site as well as in the laboratory. Theemployment of automatic sampling equipment - e.g. with several, independently andsubsequently controllable absorption receptacles - allows continuous anduninterrupted measurements. Analyses can be carried out with an automaticapparatus in the laboratory.One specific example is the measurement of dust deposition. This is in principle adiscontinuous, manual measurement method, but because of the length of theexposition time of one month without breaks for a single measurement, it is termedsemi-continuous.Continuous measurements have the advantage of providing temporarily unbroken airmonitoring. They are predestined for stationary employment, but it is also possible tofit them in mobile monitoring laboratories. Since higher temporal than spatial variationis to be expected for air pollution in city areas with widely distributed pollutants - suchas SO2 -, continuous measurements provide advantages for air quality monitoring.For the implementation of Smog Regulations continuous measurements areindispensable. Expenditure for automatic continuous measurements is high: themeasurement equipment is quite expensive and highly qualified personnel is neededfor its operation. Therefore, equipment for continuous ambient air qualitymeasurements has been developed so far only for a limited number of substances.Discontinuous, manual ambient air quality measurement methods are most useful forrandom sampling, and for covering many measuring sites in an examination area.Often, the measurements apparatus can be employed for the detection of severaldifferent substances. Finally, this working area covers the measurement of all thosesubstances for which no automatic equipment is available.2. Continuous MeasurementsContinuous ambient air quality measurements are carried out mainly for theimplementation of government regulations in particular of the European Community.The German law specifies that listings of suitable measurement equipment forcontinuous measurements shall be published by the Federal Minister for theEnvironment, Nature Protection and Nuclear Safety (BMU) following consultation withthe responsible authorities of the individual Federal States. These publications shallbe made in the Joint Ministerial Gazette. 18
  19. 19. 2.1 Suitability TestsThe publication of suitable equipment for continuous ambient air qualitymeasurement by the BMU requires the successful completion of a suitability test. Anexamination schedule for suitability tests, which has been designed by experts ofofficial Federal and local government institutions and has been approved.A suitability test is normally carried out following a request by the measurementequipment manufacturer to one of the institutes named above. On completion of thesuitability test, which is carried out at the manufacturers expense, the instituteprovides a test report to the Federal Environmental Agency (UBA). If theirassessment is positive, publication follows as mentioned above in the JointMinisterial Gazette by the Federal Minister for the Environment, Nature Protectionand Nuclear Safety (BMU).2.2 Description of Continuous Ambient Air Measurement EquipmentDetailed descriptions of quite a number of continuously operating ambient air qualitymeasurement devices can be found in Guidelines by the Commission on Air PollutionPrevention in the Association of German Engineers (VDI/DIN). These Guidelinesdescribe continuously operating measurement devices for the measurement ofsulphur dioxide, nitrogen oxide, carbon monoxide, ozone, sum of organic compoundsand suspended particulate matter.2.3 Measurement PrinciplesSuitability-tested, continuously operating ambient air quality measurement devicesare available for the following air polluting substances:- sulphur dioxide,- nitrogen oxides,- carbon monoxide,- ozone,- total gaseous organic compounds,- benzene,- toluene, ethyl benzene, xylene and- suspended particulate matter, PM10, PM2.5.The measurement principles employed by these instruments are briefly described inthe following. In most cases they correspond to the methods used for continuousemission measurements so that the descriptions have partly been borrowed from theEmission Manual.2.3.1 ConductometryIn the conductometric measurement principle the sample gas is introduced into asuitable liquid reagent and the change of the conductivity is measured aftercompletion of the reaction between the liquid and the gas. Objects of measuring aremainly sulphur dioxide and carbon monoxide.In continuous conductometry the sample gas and the reagent liquid are continuouslydelivered into the reaction cell. As the conductivity is dependent on the ratio ofsample gas to the liquid volumetric flow, suitable means must be provided to ensure 19
  20. 20. that the flow of both streams is kept constant. The influence of temperature on theconductivity must be compensated.2.3.2 Chemiluminescence MeasurementSome chemical gas reactions produce a characteristic radiation, the so-calledChemiluminescence. The intensity of this Chemiluminescence is proportional to themass flow rate of the sample gas under constant reaction conditions, if the auxiliarygas necessary to produce the reaction is present in excess.The Chemiluminescence emitted during the oxidation of nitrogen oxide moleculeswith ozone is used in the determination of NO concentration: NO + O3 —¥ NO2 + O2+ hv.Chemiluminescence measurements take place in a reaction chamber. Air which hasfirst passed through an ozone generator flows into this chamber. The partialconversion of the oxygen in the air to ozone is accomplished by electrical dischargesor by UV irradiation. A constant flow sample gas enters the reaction chamber viaanother entrance nozzle and is mixed with the ozone rich air. An ozone filter is fittedin the outlet of the reaction chamber to prevent pollution of the environment. Thechemiluminescence, after being optically filtered, is measured with a photomultiplier.A thermostatically temperature controlled reaction chamber operating at a constantinternal pressure is absolutely necessary to obtain a stable measurements.For the determination of the nitrogen dioxide concentration, the sample gas is firstpassed through a thermocatalytic converter which reduces NO2 to NO before theanalysis is performed.This method is also used to measure ammonia in ambient air. For this purpose, NH3is transformed into NO, and the amount of NH3 in the sampling air is determined bymeasuring the difference to the previous amount of NO.The principle of chemiluminescence is also employed for ozone in ambient air qualitymeasurements (Table 7). Here also the reaction of O3 and NO (in excess) describedabove is used for continuous measurements.2.3.3 UV Fluorescence MeasurementThe sample air passes through a beam of light from a UV lamp (e.g. Zn-hollowcathode lamp). As a result the molecules of the gas to be measured are activatedinto a fluorescence radiation which is led into a photomultiplier as a receiver and canbe measured after amplification. An interference filter placed before the receiverfilters out the specific fluorescence radiation of the gas to be measured. Thefluorescence intensity is a function of the concentration of the gas to be measuredand the light energy of the UV light source.The method is employed as an ambient air quality measuring technique for thecontinuous measurement of sulphur dioxide. It also enables the measurement ofhydrogen sulphide. Before the measurement H2S is oxidized to SO2.Measurement by Non-Dispersive Infrared Absorption and Gas Filter CorrelationAll heteroatomic molecules like CO, CO2, SO2 and NO possess a typicalcharacteristic absorption spectrum in the infrared range. In ambient air qualitymeasurement, the principle of infrared absorption is employed exclusively for themeasurement of carbon monoxide (CO) and carbon dioxide (CO2), because the 20
  21. 21. radiation absorption of these gases is high enough even in low concentrations inatmospheric air.The non-dispersive infrared absorption methods (NDIR) dispense with the spectralrefraction and obtain the desired selectivity by the use of a sample of the measuringcomponent stored in the instrument itself. Depending on the method of storing thesample, the non-dispersive infrared absorption method (NDIR) and the gas filtercorrelation method (GFC) are distinguished.The NDIR method uses the light receiver for storage. The radiation transformed inthe gas filled receiver chambers and modulated by a revolving chopper wheelproduces periodic pressure variations in the receiver chambers. These are sensed,either by a membrane capacitor, or in a micro flow detector which senses thepressure equalizing flow between each of two receiver chambers, and converted intoelectrical signals.The gas filter correlation (GFC) method uses a gas filled chamber fixed to a filterwheel. This filter chamber and either an opening or a N2 gas filled filter arealternately and periodically brought into the light path.2.3.4 Measurement of UV AbsorptionUV absorption measurement is employed for continuous measurements of ozone inambient air. The measurement is based on the absorption of ultraviolet light byozone, which has a maximum wavelength of 254 nm.The sample air is passed into a measurement cell, which is placed between the UVradiation source and the radiation receiver (i.e. a photomultiplier). The air is passedinto the cell by means of a magnetic valve alternating between direct flow and flowthrough a catalytic converter, which quantitatively reduces ozone to oxygen. Theradiation intensity measured in ozone free air is stored and subtracted from theintensity measured in the air containing ozone.2.3.5 Flame lonisation MeasurementOrganic carbon compounds are relatively easily ionizable in a hydrogen flame. In anionization chamber the ion cloud thus produced is extracted by applying an electricfield via electrodes and generates an electric current. This current is, to a largedegree, approximately proportional to the mass flow rate of organic bound carbonatoms. There is, however, a certain dependence on the structural bond of the Catoms of the particular molecule.The flame ionization detector consists of a combustion chamber. Pure hydrogen,which can be taken from a pressurized gas cylinder or produced in an electrolytichydrogen generator unit, flows through a nozzle into the combustion chamber.Combustion air from the atmosphere is admitted via an annular slit around thenozzle. After electrical ignition, a steady hydrogen flame produces a very small iondensity (zero value) in the absence of organic carbon compounds in the sample gas.The electrodes necessary to extract the ion cloud are arranged near the flame. Thecombustion nozzle itself can be used as one of the electrodes. With a sufficiently highelectric potential difference, all the charge carriers will find their way on to theelectrodes, i.e., the saturation current is flowing. This is raised to the desired signalamplitude by a sensitive direct depends on the material of the combustion nozzle and 21
  22. 22. the detector geometry. For continuous measurements the temperature and the massflow rate of the sample gas must be kept constant.For ambient air quality measurements, the determination of the sum of gaseousorganic compounds is current amplifier, and at the same time, the zero value iscompensated. The absolute measuring sensitivity performed after the separation ofmethane, which is always contained in samples but hygienically negligible. Theseparation can be obtained by placing before the FID either a short separationcolumn or a cooled storage column or by catalytic burning of hydrocarbons, takingadvantage of the fact that they have a larger mass than methane.2.3.6 Optical Long-Path Monitoring (Path-Integrating Measurement)Optical long-path monitoring techniques for air quality monitoring have already beenused for years for various measuring tasks, particularly for the registration ofemission rates and for air-chemical as well as meteorological research. The followingoptical techniques for gas long-path monitoring are designated and described:- Lidar- Derivative Spectroscopy- Differential Optical Absorption Spectroscopy (DOAS)- FTIR-Spectroscopy (Fourier-Transformation-Infra-Red)- Correlation Spectroscopy.Optical long-path monitoring does not include sampling by suction of air. Thismeasures the radiation absorption which occurs when a defined beam passesthrough an air distance of the gas to be analysed.Long-path monitoring is usually closer to emission measurements than to ambient airquality measurements. The pollution concentrations close to emission sources isoften measured. Detection limits and interferences caused by fog, dust and othersubstances limit the use of long-path monitoring for ambient air qualitymeasurements.The optical long-path monitoring technique (DOAS) is based on the absorption of UVlight or visible light by the gas to be measured on a length up to several kilometersbetween a light emitter and a receiver system. It proved efficient for ambient airquality measurement as for instance by the suitability test of an instrument formeasurement of sulphur dioxide. Instruments for measuring nitrogen oxide, ozoneand benzene are currently undergoing suitability tests.2.3.7 Automated Gas ChromatographyThe principle of gas chromatography is also used in new suitability tested devices forcontinuous-automatically measurement of aromatic hydrocarbons (benzene, toluene,xylene, ethyl benzene) in ambient air. Minimum requirements and examination fordevices measuring automatically for individual measurements of benzene in air withenriched sampling and subsequent gas-chromatographical separation are describedin the DIN-norm 33963-2.Particularly the measurement of benzene as an air-hygienically critical component ofmotor vehicles exhausts is a priority of air quality supervision today. 22
  23. 23. 2.3.8 Measurement with Beta-Ray AbsorptionIn dust measurement with beta-ray absorption systems, the sample air is suckedthrough a filter tape which is getting moved stepwise. The dust quantity precipitatedon the filter tape is measured by the gradual attenuation of the beta-ray radiation thatis passing through the dust laden filter.A synthetically manufactured radioactive probe of suitable activity (e.g. carbon 14 orkrypton 85 isotopes) is used as the radiation source and a Geiger-Müller counter oran ionisation chamber employed for the detection. To compensate for the gradualreduction in radioactivity over a period of time and the variation of the radiationweakening due to the filter material, measurements of the absorption are takenbefore and after, or before and during dust filtration and the measured valuescompared with each other. During the absorption measurement, while dust sampling,the accumulated particle mass is measured and indicated. Generally, the double-beam compensation method is employed in devices of this kind. This facilitates areal-time measurement of dust on the filter. Planning of ambient air quality measurements General rulesContents1 Problem analysis1.1 Content of the task description1.2 Analysis of background information1.3 Assessment of the results of the measurements1.4 Measurement parameters, measurement area and measurement period1.5 Requirements on the results2 Organization2.1 Project management2.2 Personnel planning2.3 Scheduling2.4 Subcontracts3 Measurement techniques3.1 Time resolution of the measurements3.2 Performance characteristics3.3 Standardization of the measuring procedure3.4 Infrastructure for using measurement techniques3.5 Data recording and documentation of the measurements4 Measurement strategy4.1 Measurement locations4.2 Measurement times4.3 Sampling period4.4 Duration of the measurement program4.5 Supplementary measurements5 Evaluation5.1 Producing measured values5.2 Evaluation algorithms5.3 Measurement uncertainty5.4 Uncertainty of the result 23
  24. 24. 6 Quality assurance7 Reports1 Problem analysisThe intention of the requirements described here is for the planning of ambient airquality measurements to be completed so as to enable a given task description to beprocessed with sufficient conclusiveness and with an acceptable outlay. This shouldensure that the results gained from the measurements will meet the requirementsstipulated in terms of the data being representative and with regard to themeasurement uncertainty.This is an aid to everyone involved in the planning, performance or evaluation ofambient air quality measurements. Basic knowledge in the following fields is useful:- assessment of air pollution and its effects,- chemistry of air,- measurement techniques in the field of trace analysis,- meteorology,- statistics,- quality assurance.The aim of problem analysis is to differentiate the investigation task so that appropriate andunambiguous technical stipulations can be defined for carrying out the investigations. In orderto do so, the following must be analyzed:- what objective is to be achieved,- what background information concerning the problem is available,- how the results of the measurements are to be assessed,- which air quality characteristics, which measurement area and whichmeasurement period are to be studied.1.1 Content of the task descriptionA specific task description is required in order to plan the measurements. The task isconsidered to be described with sufficient clarity if it allows stipulations to be madeconcerning the following points:- air pollutants to be investigated,- assessment standards to be applied,- measurement techniques, including sampling,- measurement area and density of measuring sites or measurement locations,- duration of an individual measurement, frequency and period of measurement,- quality assurance,- evaluation and report.1.2 Analysis of background informationThe problem analysis phase includes gathering information which will allowclassification of the task. Before a measurement task is formulated, a model conceptis usually developed to determine a causal relationship between the occurrence of airpollution at a location or within an area under consideration and its possible effectson a group of objects to be protected or an individual from such a group. The extentto which a planned investigation using techniques to measure the respective airpollution in the atmosphere can help to answer the question raised will depend,among other things, on how realistic this model concept is. It can be used to analyze 24
  25. 25. how the problems presumably caused by air pollution in the area in question can bedescribed adequately and how they can be investigated using measurements andwhether an investigation task requires further detailing.Starting points for the analysis are matters concerning measurement data available,sources which contribute to the occurrence of air pollution within the measurementarea, and effects on the objects to be protected.Analysis of measurement data availableIf results of surveys on air pollution carried out within the measurement area areavailable, they may provide important information for the planning of furthermeasurements. If the measurement area contains one or more permanent measuringstations, these should be taken into account when planning the measurements. Themeasurements recorded by these permanent measuring stations may be included inthe evaluation. The same applies to any meteorological data available.Analysis of the sourcesTo determine the air pollution occurring within the measurement area, it may benecessary to carry out an analysis of the sources present within the measurementarea and its vicinity and of the emissions from such sources. This requires expertknowledge in plant and process engineering. In this context, it may also be helpful toanalyze any emission survey charts which may be available. Generally the followingtypes of sources are distinguished:- industrial facilities,- small industry and house fires,- traffic,- natural sources.Any sources of emissions with a low outlet or stack height are extremely significantfor the occurrence of near-ground air pollution within a measurement area. Sourceswith higher stacks contribute to a lesser extent to the occurrence of near-ground airpollution near to the source owing to the greater dilution of the emissions on theirdispersion paths. In many cases, dispersion calculations can be applied to estimatethe anticipated proportions from known sources in the air pollution within themeasurement area. Provisions covering such calculations are laid down in pertinentguidelines and procedures. The result of these analyses should be a register of typesof air pollution anticipated. Information on the sources or types of sources causingthe pollution should be included in the register.Effects of air pollutionWhen planning the measurements, it is also useful to know what effects may becaused by air pollution on objects to be protected and what hazards may be involved.The following outline will show how important this is. A precondition for the effect ofair pollution on an object to be protected is firstly the contact of the object with the airpollutants. Such a contact can take place either directly by direct exposure orindirectly (however, the indirect effect of trace substances relevant to the climate, forexample, will not be examined here). In the case of man as the object to beprotected, there is direct contact, e.g. by inhalation and additionally throughunprotected skin, as well as indirect contact which is mainly through the food chain.In contrast to indirect contact over which man has a certain amount of control bysuitable preventive measures (control and selection of food), it is generally verydifficult to apply acceptable measures to prevent direct exposure when the substance 25
  26. 26. has already escaped into the atmosphere. Since effects are usually determined bythe mass of a substance absorbed, the duration of exposure and the pattern ofexposure over time, the differences mentioned may be significant when stipulatingthe measurement strategy to assess the impact of a pollution situation. Additionally,in the case of direct exposure, consideration should be given to the fact that thedifferent pollutants can have different effects on the objects to be protected. Forinstance, acute effects may occur due to the effect of high concentrations ofparticular substances (e.g. irritant gases such as ozone, sulfur dioxide or nitrogendioxide), and chronic effects may occur due to an accumulation of possibly extremelylow concentrations of various substances (e.g. heavy metals such as lead orcadmium). As far as measurements are concerned, the carcinogenic substances(e.g. benzene, benzo(a)pyrene or asbestos) shall be treated in the same way as thecumulative substances. Such aspects should therefore also be taken into accountwhen stipulating measurement strategies.1.3 Assessment of the results of the measurementsInternational and national assessment standards are derived from the informationgained concerning interrelations between exposure and observed effects. Forinstance, assessment standards are included in national environmental legislationwith the associated Regulations and Administrative Orders and in correspondingExecutive Orders. The assessment standards include, for example, action values,threshold values, test values and recommended values. The applicable assessmentstandards form the basis to derive air quality characteristics which are to bedetermined within the framework of the measurements.1.4 Measurands, measurement area and measurement periodThe problem analysis shall include verifying whether the measurands to be collected,the measurement area and the measurement period have been stipulated in anunambiguous and targeted manner. In doing so, any appropriate environmentalprovisions shall be observed. In this context, it should now be clear whatsupplementary information (e.g. results from preliminary investigations) is required tocarry out the investigation task.1.5 Requirements on the resultsDuring the detailing of the task description, stipulations shall be made with regard tothe air quality characteristics (characteristic values) to be determined, therequirement on the measurement uncertainty, and the requirement on howrepresentative the measurements are to be in terms of area and time.It is important to stipulate these boundary conditions since they have a majorinfluence on the outlay required for the measurements. Reference shall be made topertinent standards and guidelines if these can be applied to specify the aboverequirements.2 Organization2.1 Project managementThe person appointed as project manager shall have the knowledge and practicalexperience required for planning and carrying out ambient air quality measurements.A suitably qualified deputy project manager shall also be appointed. Verification oftheir qualification may be provided. 26
  27. 27. 2.2 Personnel planningPlanning of the personnel resources required to carry out the measurements shalldepend on the measurement task set. The personnel shall have relevant experiencewith the measuring procedures used. Measurement technicians and their assistantsshall have acquired their knowledge through practical work in the field of air qualitymeasurements. A technical qualification and knowledge of electronics and computersare an advantage.2.3 SchedulingPlanning and organizing the schedule to carry out the measurements will depend onthe measurement strategy and the measurement procedures. The time sequenceshall be documented. In the case of measurements based on random samples,alternative dates shall be planned for the event of any measurement gaps.2.4 SubcontractsSubcontracts should only be awarded for precisely defined tasks. The qualification ofthe subcontractors to carry out the task shall be verified by provision of documentedevidence (e.g. quality assurance manual. Any subcontractors participating in ameasurement contract shall be specified in the measurement plan. 27
  28. 28. 3 Measurement techniquesWith regard to the measuring procedures to be used, stipulations shall be laid downconcerning sampling, analytical determination and data production. The measuringprocedures will be selected in accordance with the measurement task. The results ofthe measurements must meet the requirements set. When selecting themeasurement techniques, the following points shall be examined in particular:- Will the required temporal differentiation be achieved using the measuring procedure?- Are the performance characteristics of the procedure sufficient with regard to the task description?- Is a standardized measuring procedure required for the measurement task?- Can the infrastructure necessary for the measurements be provided?- Is the measuring procedure sufficiently documented?Continuous measurements comprise uninterrupted recording of air pollutionthroughout the measurement period (apart from interruptions for calibration,servicing, etc.). If automatically recording measuring instruments are used, sampling,analytical determination and data production can be carried out in situ. In thesecases, the data is recorded using line recorders and/or data-recording computers andmemories. Any non-recording measuring instruments are usually used forsupplementary procedures, and the measurements need to be evaluated in thelaboratory at specific intervals.Discontinuous measurements provide individual, non-connected measurement data(measurements of random samples). Therefore they do not provide full informationthroughout the measurement period. The number and times of measurements ofrandom samples shall be selected to correspond to the measurement strategystipulated and to meet the requirements set for the results of the measurements. Formany measurement tasks, it is customary to stipulate the number and temporaldistribution of measurements of random samples giving due regard to the statisticaluncertainties involved.Semi-continuous measurements exist, according to the above definition, if the resultsof discontinuous measurements do not differ by more than 5% from the results of thetheoretically correct, continuous measurements over the reference period. In thecase of different air pollutants, the requirements may vary greatly and will bedependent on the respective time constant with which the concentrations may rapidlychange. Measurements will be semi-continuous in cases where a discontinuousmeasuring procedure is used to carry out measurements which as far as possible arecontinuous over the relevant period.With the aid of automatic measurement techniques (robots), it is now possible toconvert some discontinuous measuring procedures into semi-continuous proceduresat an acceptable effort, e.g. by automatic exchange of the sampling medium(accumulation material) and subsequent on-the-spot evaluation (e.g. benzene). Forthis purpose, a particular time cycle can be specified for the individual measurementsup to continuous recording.3.1 Time resolution of the measurements 28
  29. 29. The time resolution of the measurements shall be in accordance with the air qualitycharacteristics to be determined. For continuously recording measuring instruments,the time periods can be divided up on a broadly variable basis. These will not providegenuinely instantaneous values. The shortest possible integration time will dependon the measurement arrangement, the response time of the instruments, thesampling cycle, etc. In the case of measurements taken by non-continuouslyrecording instruments, the time resolution will be determined primarily by the typeand duration of sampling required to achieve given performance characteristics of theprocedure, above all in this case, the detection limit. 29
  30. 30. 3.2 Performance characteristicsThe requirements for the performance characteristics of the measuring procedure tobe used (e.g. detection limit, confidence range, cross-sensitivity) shall be based onthe assessment standards and on the level of the concentrations or depositsanticipated. The detection limit of the measuring procedure should in any case beless than 10 % of the assessment standard. This must be ensured with acceptableoutlay in terms of quality control and documented in a reproducible manner. Thefrequency and scope of calibration required shall be stipulated in the measurementplan. The reference materials, reference measuring procedures and test gases to beused shall be specified. The performance characteristics specified for standardizedmeasuring procedures in guidelines and standards and in suitability test reports formeasuring instruments can be used as a guide when selecting the measuringprocedure. The analytical function of the measuring procedure used shall be verifiedat regular intervals. When using non-standardized measuring procedures, theperformance characteristics shall be redetermined whenever the operatinginstructions are amended. The performance characteristics shall be recordedaccurately and attached to the reports of the results.3.3 Standardization of the measuring procedureTo guarantee uniform practices in the monitoring of ambient air quality throughout theFederal Republic of Germany, stipulations relating to measuring procedures andmeasuring instruments are set out in general Administrative Orders. Standardizedmeasuring procedures are listed in the 4th Administrative Order on Air PollutionControl. Continuously operating measuring instruments shall meet minimumrequirements and this shall be verified in comprehensive suitability tests at anapproved test institute. The performance characteristics and possible applicationsshall be documented in the test report. Lists of approved measuring instruments willbe published in the Joint Ministerial Gazette by the relevant ministry in agreementwith the supreme state authorities responsible for air pollution control.Wherever there are appropriate guidelines or standards, only standardizedmeasuring procedures should be applied. The documentation shall include the name,origin and number of the guideline or standard.If no standardized measuring procedures are available, the measuring procedureused shall be documented in a comparable manner. Methods and operatinginstructions shall be prepared giving sufficient detail to ensure that the sequence ofthe investigation can be retraced precisely at any time. The performancecharacteristics shall be redetermined whenever the operating instructions areamended. The operating instructions shall be numbered and kept in the archives.3.4 Infrastructure for using measurement techniquesFor the measurement techniques to be employed, a specific infrastructure must beavailable or be able to be provided with acceptable outlay. In this context, thefollowing aspects shall be examined:- Is there a guaranteed energy supply to meet requirements (e.g. secure against being switched off or against power failure if supplied by a third party)? 30
  31. 31. - Are the measuring procedures affected by the weather (temperature, humidity, sunlight, frost), and is there a suitable measurement location available e.g. air- conditioned measuring room or vehicle, if required?- Are the measuring instruments sufficiently insensitive to vibrations, for instance during transportation? (This applies particularly to use in measuring vehicles.)- In the case of measuring instruments operating unsupervised, can outside manipulation be ruled out?- In the event of measuring instruments breaking down, are spare parts or replacement instruments available at short notice to reduce interruptions? 31
  32. 32. These points of infrastructure shall be taken into account when selecting themeasurement techniques.3.5 Data recording and documentation of the measured valuesAll raw data required for the evaluation and traceability of the measurements shall bedocumented and stored. Before the measurements begin, suitable measurementreport sheets and, for laboratory evaluations, sample record forms shall be prepared.The way in which the measurement data is to be recorded shall be described in themeasurement plan. Wherever possible, the data should be recorded using electronicdata processing facilities. The main factor is to achieve guaranteed and traceabledata storage. The storage periods shall be stipulated.The measurement data shall be validated by an independent internal control body.The validated measurement data shall be identified as such and stored in such a waythat they can only be amended using control codes. Details relating to anycalibrations carried out as well as servicing work, instrument inspections, anymalfunctions, etc. shall likewise be documented. Furthermore, the data evaluationtechniques and the algorithms of statistical methods shall be documented and storedin such a way that the evaluation can be retraced at any time.4 Measurement strategyWhen using measurements to investigate air pollution, the "air pollution object"measured generally has both a temporal and a spatial structure. The measurementstrategy to be stipulated should be a realistic reflection of the temporal and spatialconditions occurring on the object measured during the measurement period withinthe measurement area. The temporal and spatial distribution of the measurements tobe carried out, i.e. the measurement strategy, determine the quality or"representativeness" of this reflection. This means that the representative nature ofan investigation of the air quality is not an absolute, but is a measure of the quality ofthe reflection, by the temporal/spatial random sample collected, of the conditionswhich have occurred on the "air pollution object" measured. This is also greatlyinfluenced by the measurement outlay.Continuous measurements can be carried out, for example, to achieve a nearlyuninterrupted reflection of the temporal structures of the air pollution investigated atthe measurement locations. This means that the investigation will be highlyrepresentative in terms of time. In contrast, complete recording of the spatialdistribution of the types of air pollution under consideration within a largemeasurement area is nearly impossible. Investigations of air pollution usingmeasurements in large measurement areas will therefore be of the random sampletype, at least in terms of area. The representativeness of the results of randomsample investigations is generally limited and may be described by the survey-relatedproportion of the uncertainty of the result.When planning the measurements, the question is raised as to how these sample-related uncertainties in the investigation of air pollution can be controlled. Thetemporal and spatial density of the measurements and the existing temporal andspatial structures of the object measured are all deciding factors. For this reason, the 32
  33. 33. spatial arrangement of the measuring points, the temporal distribution of sampling,the duration of individual measurements and the duration of the measurementprogram shall be stipulated in detail. On the one hand, it will then be possible for thetiming of the measurement program to range from many time periods up tocontinuous registration of the measurands. However, this is only possible for someselected types of air pollution and, for reasons of outlay, usually only at comparativelyfew measurement locations, consequently with little spatial resolution. On the otherhand, it will generally only be possible to achieve high spatial resolution at the cost ofless temporal resolution. Between these two extremes, stipulations will have to bemade which result fromthe task description and the available means. Air quality measurements will generallyonly provide random samples of the population. The reliability with which aninvestigation object can be characterized based on a random sample investigationdepends on how well it is represented, i.e. reflected, by the random samples. Animportant task of planning the measurements therefore consists in organizing theinvestigations in such a way that the random samples collected are representative ofthe investigation object, and that it will be possible to assess the effects in question, ifnecessary by comparison with relevant assessment standards. The measurandsmust be suitable to determine the air quality characteristics required to achieve theobjective.4.1 Measurement locationsRandom selection of measurement locationsA simple and reliable method of carrying out a random spatial selection consists inarranging the measurement locations in a square grid. This ensures that themeasurement locations are independent of the basic infrastructure patterns within themeasurement area, provided that these do not exhibit the same regularity as themeasurement grid selected, and this can easily be checked. Measurement locationsstipulated in this way form a representative random sample of the points covered bythe measurement area.The grid width selected will expediently limit the achievable spatial resolution of themeasurement grid produced. Thus, with a measurement grid having a grid width of1 km, it is not possible to carry out systematic recording of spatial structures of the airquality characteristics investigated if they have an extent of less than 1 km; ifappropriate, shorter distances between the measurement locations should beselected.Stratification of measurement locationsThe population of possible measurement locations within the area to be investigatedis divided into similarity strata. The elements of each stratum have commoncharacteristics which differentiate them from the elements of the other strata. Anexample of a suitable stratification is similarity with regard to the structures of use.Targeted selection of measurement locationsOnce conclusive and traceable data has been obtained, from which the anticipatedspatial structures of the air quality characteristics investigated within themeasurement area can be derived, a targeted selection of measurement locationscan be made, for example at the location where the highest values of stipulated airquality characteristics are expected. Documents prepared in a traceable manner shallbe kept to demonstrate how the selection of the measurement location was made. 33
  34. 34. 4.2 Measurement timesContinuous recordingContinuous recording of air quality characteristics is absolutely essential ifinformation is required concerning temporarily elevated concentration values, such asis the case in warning systems. In extended measuring grids, this type of recordingmay prove to be expedient for other reasons, for example reducing the personnelrequired by having unsupervised operation of automatic analyzers or collectors.Deposit values are usually determined on the basis of continuous recording. If thistype of recording is not necessary for technical reasons, preference should be givento one of the following selection procedures.Random selection of measuring timesAn equally distributed random selection of the measuring times, i.e. the starting timesfor sampling, from a given measurement period allows representative randomsamples to be chosen from the temporal distribution of the air quality characteristicsinvestigated, irrespective of whether these are half-hourly, hourly or daily meanvalues. A precondition, however, is that the individual measurements within therandom sample are independent of one another in a statistical sense. This can beachieved, for example, by collecting no morethan one sample in any sampling period of up to 8 hours per day. With a samplingperiod of 24 hours, this can be achieved by not collecting samples on consecutivedays. There are relevant regulations which give stipulations relating to samplingfrequency for ambient air quality measurements.Stratification of measuring timesAir quality characteristics often have typical time dependencies, for example dailycycles, weekly cycles or annual cycles. Conclusive and verifiable information on suchtemporal regularities can be utilized to limit the time requirement for themeasurements and thus to make them more cost-effective. For instance, if thepopulation to be investigated covers a temporal distribution over one year,information on the annual cycle can be utilized to determine annual characteristicvalues by extrapolation from shorter measurement periods, provided that the errorbands associated with this type of extrapolation are acceptable. If dependencies ofthe air quality characteristics in question relating to the time of day result in elevatedvalues during specific hours of the day, sampling carried out exclusively during thesetimes will lead to overestimates of the characteristic values in relation to the wholeday. If such overestimates can be tolerated, it is acceptable to restrict the measuringtimes to these particular hours of the day.Knowing the times of the day when the maximum air pollution impact occurs mayalso be useful for specific determination of the maximum values of the air pollutionimpact. In this way, if guide values are not exceeded, for example, it can be deducedwith a high degree of certainty that the values at the measurement location have notbeen exceeded, even under unfavourable conditions.Targeted selection of measuring timesIf the proportions from a known source in the concentrations of specified airpollutants are to be recorded at a few specifically selected measurement locations, it 34
  35. 35. is advisable likewise to target the selection of the measuring times, for example as afunction of the emission characteristics of the source and the wind direction. It isespecially advisable to make a targeted selection of measuring times if themeasurements relate to effects which can be predicted to occur at specific times.This is frequently the case when investigating complaints. For instance, if theproportion of air pollution from a specific source at a given location is to beinvestigated, measuring times should be selected, on the one hand, at which animpact on the measurement location is anticipated owing to the activity of the sourceand the prevailing wind direction and, on the other hand, measuring times at whichan impact due to the identified source can be ruled out. By comparing the results ofthe two categories, the contribution from the source in question at the measurementlocation can be estimated. In this case, the determination and consideration of thewind direction is thus helpful in selecting the measuring times.4.3 Sampling periodThe sampling period depends on the assessment standard and the measurementprocedure. For discontinuous measurements, it is usually between half an hour and72 hours. Longer sampling times are also permissible if the assessment standardand the measurement procedure make allowance for this.4.4 Duration of the measurement programThe duration of the measurement program is to be specified in the measurementplan. In many cases, the duration of a measurement program can be deduced fromthe air quality characteristics in question. If, for example, annual characteristic values,such as the annual mean value or the 98-percentile, are to be determined, themeasurement period should always cover 12 months. Deviations from this period arepermissible in exceptional circumstances. 35
  36. 36. If information is available concerning seasonal differences in the impact caused bythe types of air pollutants in question, this information can be used for some taskdescriptions to arrange for the measurements to be taken only in the six-monthperiod with the higher air pollution impact. Shortening the measurement period to 6months is also acceptable if the air pollutant investigated has not been shown tohave an annual cycle. The characteristic values derived for a six-month period arethen used as estimated values for the annual characteristic values required.If the investigation relates, for example, to the frequency with which the ozoneconcentrations at a measurement location exceed the threshold value of 180 μg/m3,the measurements can be limited to the summer half-year since such concentrationsare not experienced in the winter half-year.For measurements taken for orientation purposes, the measurement period may bereduced down to one month, provided that extrapolations known to be reliable can becarried out to estimate the annual characteristic values required.4.5 Supplementary measurementsIt will often be necessary to carry out supplementary measurements to achieve themeasurement target. These may include meteorological parameters if suchinformation cannot be acquired from other sources. Other important parameters mayalso be details of traffic structure, such as type of vehicle, vehicle density or traffic.5 EvaluationThe rules of calculus used when evaluating the measurement data are generallyrequired,- to obtain measured values from the measured signals,- to determine the air quality characteristics in question from the measuredvalues, and- to estimate measurement uncertainties.More thorough statistical evaluations, e.g. for causal analysis or the planning ofpreventive measures, can be based on the above.5.1 Producing measured valuesIn order to ensure that the measurement process is reproducible, the analyticalfunctions used, their parameters and the associated standard deviations andcovariances must be documented and included in the measurement report.5.2 Evaluation algorithmsMathematical algorithms are usually needed to determine the air qualitycharacteristics required from the measured values. To ensure that the evaluationsare reproducible, the evaluation algorithms used must be documented and includedin the measurement report in a reproducible form. It is also advisable to refer tostandardized evaluation procedures wherever possible.Detection limitFor the purpose of the evaluation, stipulations shall be made as to how measuredvalues below the detection limit are to be treated. These measured values can betaken into account, for example, using half the value of the detection limit. 36
  37. 37. Measurement gapsThe proportion of measurement gaps shall be specified and reasons given in theevaluation. It may be necessary to agree a maximum permissible proportion ofmeasurement gaps. If gaps in the measurement data can be filled by calculation, thecalculation method used shall be specified. The substituted measured values shall beidentified as such. 37
  38. 38. OutliersThe treatment of outliers shall be specified and reasons given. The measured valuesdetermined as outliers shall be identified as such.5.3 Measurement uncertaintyDuring planning the measurements stipulations must also be made stating how themeasurement uncertainty in the data collected is to be quantified and documented.This complies with the requirement of producing data of a known quality. Themeasurement uncertainty inherent in the measurement process can be characterizedby specifying a standard deviation or variance in accordance with therecommendations of the international publication "Guide to the expression ofuncertainty in measurement". In the simplest case, the model function used will bethe analytical function. Using the methods of uncertainty propagation described in theinternational guideline, an equation can be derived for the variance of the measuredvalues inherent in the measurement process. To do so, the variances and possiblyalso the covariances of the parameters of the analytical function describing theinfluencing factors must be known. The temporal and spatial structures of themeasured object have no influence on the measurement uncertainty since they haveto be assigned to the measured object and are thus part of the investigation. If it isimpossible to specify a suitable model function which realistically describes themeasurement process taking the dominant influencing factors into account, theprecision and accuracy of the measured values can be quantified in accordance withthe International Standard ISO 5725. Departing from the concept of the internationalguideline, the ISO 5725 series of standards does specify the precision of a measuredvalue, but not its trueness as a variance or standard deviation; this is given as a bias.5.4 Uncertainty of the resultIt should be examined separately during planning the measurements whether theuncertainty of the results (air quality characteristics) is to be determined in addition tothe measurement uncertainty. It may be necessary to stipulate what procedure is tobe applied and what additional measurement or calculation outlay this will entail.The uncertainty of the results (air quality characteristics) of an investigation of airquality based on random samples will be influenced not only by the measurementtechniques used, but also by the selection of measuring times and measurementlocations, i.e. by the measurement strategy selected. The question of how themeasurement strategy will influence the uncertainty of the result is raised wheneverconclusions are to be drawn from a limited quantity of air quality measurement datacollected to give the frequency distribution (population) of the states of the measuredobject which occurred during the measurement period and within the measurementarea. The air quality characteristics to be specified as results, such as mean value or98-percentile are functions of the measurement data collected as random samplesand as such are estimates of the corresponding characteristic values of thefrequency distribution investigated which are subject to statistical uncertainties.Additional measurement and calculation outlay is generally required to examine theinfluence of a selected measurement strategy on the uncertainty of derived air qualitycharacteristics, and planning this outlay requires specific knowledge of statisticalinvestigation planning. It is therefore advisable, wherever possible, to useinvestigation examples and to apply these to investigations using the samemeasurement strategy if necessary. However, such cases must assume that the 38
  39. 39. measurement uncertainty inherent in the measurement techniques is known. If it isonly a case of ensuring that the influence of the measurement strategy on the airquality characteristics determined is comparable, a requirement for equal temporaland spatial density of the survey to be carried out is sufficient. 39
  40. 40. 6 Quality assuranceThe measurement plan should contain quality assurance (QA) statements. Themeasurement plan should clearly describe the type and scope of the QA measures tobe applied. In particular, the details should include the calibration tests andcomparison measurements to be carried out. The relevant reference standards orreference procedures shall be specified. If appropriate descriptions are availableelsewhere, for example in the quality manual of the measurement institute, referencecan be made to such documents. The details given must be sufficient to enable theintended QA measures to be verified as corresponding to the agreements orrequirements.7 ReportsIt is important to stipulate during the planning stage how the measurements to becarried out are to be evaluated, documented and stored. If requested by the client, anagreement should be reached concerning the type and scope of reports.The measurement report should as a minimum contain details of the following points:- Task description- Measurement methods- Measurement strategy- Results- Measurement uncertainties.Planning of ambient air quality measurements – Rules for planninginvestigations of traffic related air pollutants in key pollution areasContent1 Introduction2 Problem analysis2.1 General2.2 Classification of the objective2.3 Analysis of background information2.4 Use and assessment of the measurement results3 Organization3.1 Project management3.2 Personnel planning3.3 Scheduling3.4 Subcontracting4 Measurement techniques4.1 Typical measurement and sampling methods4.2 Determining the measurement uncertainty of non-standardizedmeasurement methods5 Measurement strategy5.1 General planning sequence5.2 Preliminary measurements5.3 Monitoring measurements 40
  41. 41. 6 Evaluation6.1 Production of measured values6.2 Evaluation algorithms6.3 Measurement uncertainty6.4 Uncertainty of the result7 Quality assurance8 Reporting 41
  42. 42. 1 IntroductionAir pollution measurements are carried out to answer specific questions regarding specifiedair quality characteristics in a given area or at specified locations. A leading role is generallyplayed by questions as to the effect of air pollutants on protected objects. The object ofmeasurement planning is to analyze submitted objectives and from this to deriverequirements of the organization, the measurement method, the measurement strategy, theassessment, the quality assurance and reporting.The report details the requirements with respect to studying traffic-related air pollution at keypoints where pollution occurs. The considerations reproduce fundamental knowledge to betaken into account in the planning of traffic-related studies. This is intended to enableplanning of air pollution measurements in such a manner that any question asked can beanswered with sufficient meaningfulness and with reasonable expenditure. This is intendedto result in the fact that the measurement results obtained can be assessed with respect totheir representative nature and measurement uncertainty.Traffic-related air pollutants play an important role in urban areas in particular in the vicinityof very busy roads. Vehicle occupants as well as passers by and residents are exposed tothese air pollutants. To answer the question as to whether such air pollutants can lead toharmful effects on humans, not only is the concentration of the air pollutant of importance,but also the residence time of humans in the vicinity of the road traffic. When possible routesof pollution for residents are being studied, in addition to the outdoor air, indoor air pollutionmay also need to be taken into account. The report is relevant to all those involved with theplanning, performance or assessment of studies of traffic-related air pollution. The contentscan serve clients and contractors equally as a reference base, for example for formulatingspecifications and articles and conditions for performing studies or air quality. For themeasurement planning fundamental knowledge in the following areas is helpful:- Assessment of air pollutants and effects- Atmospheric chemistry- Methodology in the trace analysis area- Meteorology- Statistics- Quality assurance2 Problem analysis2.1 GeneralIn problem analysis, the investigation task shall be specified to the extent that an economicalsolution for the measurement method and equipment resources and for the measurementstrategy can be given. For this purpose it is necessary to analyze:- what objective is to be achieved,- how much prior knowledge exists at the object to be studied,- how the results of the measurement are to be assessed or utilized.During problem analysis it can be helpful to classify the task description as a standard casefor which provisions or recommendations exist to carry it out. Measurement planning in thestudy of traffic-related air pollutants at key pollution sites may be limited essentially to thefollowing standard cases:- preliminary measurements- monitoring measurementsIf the task description should not be adequately specified, it should be made more precise ina discussion with the client. 42
  43. 43. 2.2 Classification of the objective2.2.1 Preliminary measurementsPreliminary measurements are measurements of air pollutants which, with the lowestpossible use of resources and within a narrow time frame, give indications as to whether andat which measuring sites in a selected area, harmful environmental effects on humans arecaused by road traffic. Therefore, preliminary measurements generally have the character ofspot checks. They can be used for: providing first indications of the level of expected concentrations of air pollutants at selected measurement sites verifying with respect to analytical methodology the selection of measurement sites for carrying out monitoring in a selected area verifying decisions on the necessity of monitoring.Preliminary measurements of traffic-related air pollutants are generally differentiated frommonitoring measurements by a lower equipment requirement, a generally simpler and moremobile measurement method and a narrow time restriction. Preliminary measurements aretherefore generally considerably less costly than monitoring measurements. Under certaincircumstances, preliminary measurements can replace monitoring measurements.The results of preliminary measurements are also suitable for checking simple theoreticalmodelling treatments, since these are frequently burdened with relatively high uncertainties.This report does not deal with questions of modelling traffic-related air pollution and possibleuses of the model. Preliminary measurements can also be used to obtain initial indications ofthe level of pollution at places where it is not possible to obtain a description by modelling.2.2.2 Monitoring measurementsMonitoring measurements serve to monitor compliance or exceedance of predeterminedenvironmental assessment standards. The associated measurement resources make carefulplanning of such measurements necessary. Monitoring measurements are generally carriedout with greater frequency and over a longer period than preliminary measurements. Theyare carried out at measuring sites at which there are sufficient indications of the occurrenceof harmful environmental effects due to air pollution and at which humans receive not onlyshort-term exposure. Therefore, the selection of measuring sites for monitoringmeasurements is of great importance.In some circumstances, carefully carried-out preliminary measurements, depending on thequestion, can lead to the result that the available information is sufficient for an evaluationand monitoring measurements are thus no longer necessary.2.3 Analysis of background informationPlanning of measurements of traffic-related air pollution can make significant usage of theanalysis of existing information on the object under study. The points below shall be takeninto account in analysis of background information.a) Traffic-related air pollutantsNumerous citations may be found in the specialist literature on the effects of air pollutants onhumans. More detailed studies should be left open to experts.In addition, it should be noted whether the objects measured are primary or secondary airpollutants, since the latter are only formed by reactions in the atmosphere and only permitrestricted conclusions to be made on the originating sources. This includes, for example,ozone, which is formed, depending on the particular meteorological conditions, by reactions 43

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