The document discusses criteria air pollutants monitored by the EPA, particularly focusing on ozone, its sources, chemistry, and standards for ambient air quality. It outlines the principles of air monitoring, including the instrumentation and data analysis methods used for various pollutants, along with meteorological considerations. Additionally, it highlights the importance of quality assurance in data collection and the regulatory framework surrounding hazardous air pollutants.

1. Criteria Air Pollutants
and Ambient Air Monitoring
Topics for Discussion
• Air pollutants regulated by the EPA
• Ozone – sources, chemistry, standard,
sampling, air monitor works
• Instrumentation
• Meteorology
• How data is collected/stored
• Locating a monitor
• Documentation/Analysis of data
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2. Criteria Pollutants
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Ozone
Carbon Monoxide
http://www.epa.gov/airquality/carbonmonoxide/pdfs/COFactShe
etAugust12v4.pdf
Lead
Nitrogen Oxides (NO, NO2)
Particulate Matter (PM10)/Particulate Matter (PM2.5)
Sulfur Oxides
Reference: http://www.epa.gov/air/criteria.html
Note: covered under 40CFR part 50
National Ambient Air Quality
Standards (NAAQS)
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3. Brief comment: Ozone
• Stratospheric ozone
protects us from the
UV rays of the sun.
• Ground level ozone
at high
concentrations can
irritate the
respiratory tract and
damage plant life in
high concentrations.
How is O3 created?
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4. Chemistry of Ozone
VOCs + NOx + Sunlight + Heat = Ozone
Night Time O3 Chemistry
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5. Ambient Air Standard-Ozone
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•
To attain the ozone NAAQS, the 3-year average of the annual 4thhighest daily maximum 8-hour ozone concentration must be less
than or equal to 0.075 PPM (or 75 ppb).
The old ozone threshold value for a 1-hour standard is 0.12 parts
per million (PPM), measured as a 1-hour average concentration.
http://www.epa.gov/airquality/ozonepollution/
OSHA:
https://www.osha.gov/dts/sltc/methods/inorganic/id214/id214.html
8 Hour Average
DATE
8-Hour Average
03/02/2011
80
04/15/2011
90
09/03/2011
75
09/16/2011
100
XX/XX/2010
90
4th Highest 8-hr
XX/XX/2009
100
4th Highest 8-hr
The 4th highest
8-hour average
is:
75
This would average to 88
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6. Schematic Diagram Ozone Monitor
Air Pump
Thermistor
Hg Lamp
254nm
Absorption Cell
Photodiode
Pressure Sensor
Solenoid Valve
Ozone
Scrubber
Air Inlet
Ozone Monitors
Rack mount with ozone
transfer standard instrument
and ozone monitor.
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7. Instruments for other Pollutants
• Criteria pollutants: Ozone, SO2, NOx, CO
• Other pollutants: NH3, H2S, CO2, NOy, Total
Hydrocarbon
• VOC (volatile organic compounds)
• Laser/IR systems also used.
Air Monitor – Basic Principles
• Chemiluminescence
• UV flourescence
• Beer’s law
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8. Chemiluminescence
The chemiluminescence reaction of NO to NO2:
NO + O3 ==> NO2+ O2 + hv
http://www.k2bw.com/chemiluminescence.htm
Variations of chemiluminescence have been used to
perfom measurements of Ammonia (NH3):
NH3 + O2 ==> NO + H2O
or:
4NH3 + 5O2 = 4NO + 6H2O
then:
4NO + 4O3 -------->4NO2+4O2 + 4hv
Schematic of a reaction chamber under vacuum and a
Photomultiplier tube (PMT) for detection.
Principle - UV fluorescence
Principle - UV fluorescence
The UV fluorescence method operates on the principle that when the SO2 molecules contained in the sample gas
are excited by ultraviolet radiation they emit a characteristic fluorescence in the range of 220- 240 nm. This
fluorescence is measured and the SO2 concentration is obtained from changes in the intensity of the
fluorescence.
The reactive mechanism is:
(1)SO2 + hv1 ¤ SO2*
(2)SO2* ¤SO + (O)
(3)SO2* ¤ SO2 + hv2
(4)SO2*+ M ¤ SO2 + M
Here, (1) shows the excited state of the SO2 molecules that have absorbed the amount of energy hv1 by
ultraviolet radiation.
(2) shows the amount of energy, hv2 emitted by the excited molecules as they return to the ground state. (3)
shows the decomposition by the light emitted from the excited molecules. (4) shows the quenching, i.e., the
energy lost by the excited molecules colliding with other molecules.
http://www.horiba.co.uk/apsa360.htm
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9. Beer’s Law
Many compounds absorb ultraviolet (UV) or visible (Vis.) light. The diagram below shows a beam of monochromatic
radiation of radiant power P0, directed at a sample solution. Absorption takes place and the beam of radiation
leaving the sample has radiant power P.
The amount of radiation absorbed may be measured in a number of ways: Transmittance, T = P /
P0
% Transmittance, %T = 100 T Absorbance, A = log10 P0 / P
A = log10 1 / T
A = log10 100 / %T
A = 2 - log10 %T
http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/beers1.htm
Calibration-Ozone
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10. Calibration-NOx
Calibration of a
NOx Monitor. Zero
Air machine, NOx,
Multigas calibrator.
Y = mx + b
Find the calibration
curve, use this to
calculate final value for
air pollutant.
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11. TEOM 1400 Ambient PM Sampler
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12. Meteorological Parameters
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Wind Speed/Wind Direction
Air Temperature/Relative Humidity
Solar Radiation
Ultra-Violet
Ultra-Violet
• UV-A radiation refers to atmospheric radiation from 320
nm-400 nm (that's 0.320-0.400 m m). UV-A is very
important to photosynthesis and plant studies.
• UV-B is the shortest wavelength atmospheric radiation
that actually reaches the ground, and covers from 280-320
nm (that's 0.280-0.320 nm). However, it is UV-B that
causes skin cancer over prolonged exposure.
• UV-C is "extraterrestrial" solar radiation, and includes light
with wavelengths between 100-280 nm.
• Reference: http://www.yesinc.com/products/data/FAQuvrad/faq4.html
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13. Zeno Datalogger
Documentation
• Quality Assurance Project Plan (QAPP)
– Calibration of instrumentation, how data is processed
and stored
• Site Operations Procedures (SOP)
– Calibration of instruments
– How to troubleshoot equipment
– Setting up a site
• Logbook for each site
• Logbook for each instrument
• Atmospheric Research & Analysis Inc.:
http://www.atmospheric-research.com/newindex.html
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14. Air Monitoring Sites-Texas
Typical Site
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15. TCEQ Sites for Ambient Air Monitoring
Ozone Precursors/Air Toxics
Air Toxics - There are currently 188 hazardous air pollutants (HAPS), or air toxics, regulated under the Clean
Air Act (CAA) that have been associated with a wide variety of adverse health effects. A subset of the 188
toxics thought to have the greatest impact on the public and the environment in urban areas has been identified
as the Urban Air Toxics Strategy compounds of interest. This subset of 33 compounds includes volatile
organics, semivolatile organics, and metals. Two of the six compounds identified as the risk drivers in the
strategy, benzene and 1,3-butadiene, are volatile organics which are amenable to AutoGC analysis. Data for
these two target compounds as well as all other target compounds from this analysis are forwarded to TCEQ
Toxicology Section to identify any potential health impacts that might be associated with exposure to the
measured concentrations. Ref: http://www.tceq.texas.gov/airquality/monops/agc/agc_support.html#why
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16. GC-MS Analytical System
Sample Canister
Mass Spectrometer
Gas Chromatograph
Pre-concentrator
ANALYSIS AND
COLLECTION OF DATA
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17. Automated Data Collection
Databases
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The first source is the state.
http://www.tceq.texas.gov/agency/air_main.html
EPA keeps an extensive database of monitoring sites.
http://www.epa.gov/ttn/airs/airsaqs/
Free data available for meteorology, terrain. NOAA,
NASA, many others.
• http://www.webmet.com/
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18. Ozone Concentrations vs Wind
Time Series Graph
September 29, 2004
120
80
60
40
20
23
21
19
17
15
13
11
9
7
5
3
0
1
Ozone-ppb
100
Time
AP
HR
VI
CAMS04
CAMS21
Kingsville
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19. Statistics
• Average, median, frequency analysis.
• Box-whisker plots.
• Trend analysis.
Wind Rose
•
Reference: http://www.questconsult.com/papers/weather-variations-qra/
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20. Pollution Rose
• Can be used for
evaluating the
common direction of
pollutants
• Useful for ozone, PM,
SO2, VOCs.
Direction of Sources
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Non parametric regression
Positive Matrix Factorization
Conditional Probability Function
Can be used for:
– Particulate Matter
– VOC’s
• Not appropriate for ozone
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21. Air Parcel Trajectories
REFERENCES
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Criteria Pollutants: http://www.epa.gov/air/criteria.html
Air Monitoring SOP’s: http://www.atmospheric-research.com/
Zeno Datalogger Manual
Quality Assurance Handbook for Air Pollution Measurement Systems
Volume II Ambient Air Quality Monitoring Program
http://www.epa.gov/ttnamti1/files/ambient/pm25/qa/QA-HandbookVol-II.pdf
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