The document discusses ambient air sampling methods. It defines ambient air as the air external to buildings that the public can access. Several air sampling techniques are described, including absorption in liquids, adsorption on solids, and freeze-out sampling to capture air pollutants like gases, vapors, dust and fibers. Common air pollutants measured through sampling include particulate matter, ozone, nitrogen dioxide, carbon monoxide and sulfur dioxide. Selection of sampling methods and filters depends on the phase and identity of the pollutant being measured.

1. SAMPLING OF AMBIENT AIR
POLLUTANTS
TO: Dr. KIRAN HINA
1

2. GROUP#01
• Fiza Farooq (Introduction)
• Hajra Kanwal
• Fareeha Ayoub
• Ezza Ijaz
• Laiba Shaheen
• Maryam Shehzadi
• Fatima Aslam
• 21011561-022
• 21011561-017
• 21011561-054
• 21011561-083
• 21011561-002
• 21011561-007
• 21011561-164
2

3. AMBIENT AIR
• Ambient air means that portion of the atmosphere, external to
buildings, to which the general public has access.
• Helps companies measure air quality and determine what
safety precautions they need to take.
• To detect air pollutants such as gases, vapors, dust, and fibers,
specialized devices are employed.
• Measures the quality of all the air in a particular place.(WHO)
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4. AIR SAMPLING
• Used to determine what airborne contaminants are present in
an environment.
• It is used in industrial environments to protect workers and
prevent environmental and product contamination.
• Investigators must consider not only the sampling method but
also the phase and identity of the pollutant or particulate of
interest. (BMC public health)
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5. WHAT IS AMBIENT AIR SAMPLING
• The World Health Organization (WHO) defines ambient air pollution as
potentially harmful pollutants emitted by industries, households, cars,
and trucks. Of all of these pollutants, fine particulate matter has the
greatest effect on human health.
• Most fine particulate matter comes from fuel combustion from vehicles,
power plants, industry, households, or biomass burning.
• WHO estimates fine particulate matter causes 25% of lung cancer
deaths, 8% of chronic obstructive pulmonary disease (COPD) deaths,
and 15% of ischaemic heart disease and stroke.(David Sherwin et.al
2017)
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6. Common Air pollutants
• Particulate matter (PM10 and PM2.5)
• Ozone (O3)
• Nitrogen dioxide (NO2)
• Carbon monoxide (CO)
• Sulphur dioxide (SO2)
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7. Pm2.5 and Pm 10
• Particles are defined by their diameter for air quality
regulatory purposes.
• Those with a diameter of 10 microns or less (PM10) are
inhalable into the lungs and can induce adverse health effects.
• Fine particulate matter is defined as particles that are 2.5
microns or less in diameter (PM2.5).(US EPA)
• The greatest sources of CO to outdoor air are cars, trucks and
other vehicles or machinery that burn fossil fuels. (US EPA)
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8. NOx and SOx and their sources
• NOx pollution is emitted by automobiles, trucks and various non-road
vehicles (e.g., construction equipment, boats, etc.) as well as industrial
sources such as power plants, industrial boilers, cement kilns, and
turbines. (US EPA)
• The largest source of SO2 in the atmosphere is the burning of fossil
fuels by power plants and other industrial facilities. Smaller sources of
SO2 emissions include: industrial processes such as extracting metal
from ore; natural sources such as volcanoes; and locomotives, ships
and other vehicles and heavy equipment that burn fuel with a high
sulfur content. (US EPA)
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9. Why Ambient
Air Sampling
Matters?
• Direct Impact on Health
• Effects on Ecosystems
9

10. Why we need to sample the air?
• Determining contaminant type: Using sampling equipment helps
companies know what contaminants are present and whether those
particles are toxic.
• Determining contaminant concentrations: Companies also need to
know how much of a contaminant is present in the environment.
Sampling can give them an idea of what concentrations are present so
they can determine whether the environment is safe to work in.(2019-
2020-Zefon-Catalog)
10

11. By Hajra Kanwal
21011561-017
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12. Ambient Air Sampling
• Ambient air sampling refers to the process of collecting air
samples from the surrounding environment to assess the quality
and composition of the air.
• It involves strategically placing air sampling devices or
instruments at specific locations to capture representative samples
of the outdoor air.

13. Objectives of Ambient Air Sampling
• To identify and measure air pollutants.
• To determine the effect of emission throughout the year.
• To determine the effect of emission in different zones/area
of the country.
• To assess the environmental impact of manufacturing
process.

14. Contd.
• To comply with government regulations.
• To identify the source of pollutants.
• To determine the method of control of emission
• To implement the local air pollution-control system.
• Sampling allows for quicker data collection and analysis.

15. Components of Sampling
• Amount of pollutant collected.
• Flow of air through the medium.
• Time in minutes.
• Flow × time (minutes) = volume through filter in cubic meter.
• Concentration in microgram cubic meter in ppm.

17. By Fareeha Ayoub
21011561-054
17

18. Ambient Air Sampling Methods
• There are many methods available for
collection of Air pollutants from
atmospheric Air i.e.
• Grab Sampling,
• absorption in liquids,
• adsorption on solids materials &
• Freeze-out sampling in process of
Environmental Monitoring.

19. Grab sampling method
• In grab sampling, air sample is collected by
filling an evacuated flask.
• Plastic bags have been used
• & then subjected to analysis of grabbed sample.
• Grab sample may be taken using rigid wall
containers made from glass or stainless steel.
• These containers first evacuated
• & then allow air to enter to fill the container.

20. Absorption in Liquids
• Is one of the most common method for collecting air
samples.
• To bring out high degree (pollutant) gas-liquid contact,
impingers & midget type’s devices are used. These devices
can handle sample flow rates.
• Particular absorbent-liquid (say 0.1 N NaOH) is filled inside
impinger.
• Flow is controlled with help of flow control devices.
• If done with sampling procedure, particular absorbent is then
desorbed into lab for analysis.
• Is favored by most Environmental Consultancy firms

21. Adsorption on Solids
• The air sample is passed though packed
column containing finely divided
adsorbent on whose surface pollutants
are retained.
• Commonly used adsorbent is activated
charcoal & silica gel.
• sample gases are desorbed into lab for
analysis.
• accomplished by washing adsorbent
with liquid solvent.

22. Freeze-out sampling
• Freeze-out sampling contains
series of cold traps which being
used to condensate air pollutants
from air.
• The traps are bought into
laboratory, samples are removed,
• & analysis be means of mass
spectrophotometry, Gas
Chromatography,
Spectrophotometry etc.

23. Sedimentation Method of Air Sampling
• The sedimentation method of air
sampling involves the collection
of airborne particles by allowing
them to settle onto a collection
surface under the influence of
gravity.
• This method is commonly used
for larger and heavier particles
• and is particularly effective for
indoor air quality assessment.

24. Impingement Method of Air Sampling
• Impingement method captures
microorganisms and particles by passing air
through a liquid medium.
• Entrapped particles and microorganisms in
the liquid enable subsequent analysis.
• Widely applied in microbiological air
sampling for indoor air quality assessment.
• Commonly used in healthcare settings, labs,
and controlled environments.
• Detects potential pathogens through this
technique in air quality assessment.

25. By Fatima Aslam
21011561-164
25

26. Sampling Particulate Matter
Selection of sampling filter paper
• Five types of basic collection principles employed for filter papers,
namely ‘Inertial collision effect’, ‘Screening effect’, ‘Diffusion
effect’, ‘Gravity (Precipitation) effect’, and ‘Electrostatic effect’.
• Diffusion is effective when the diameter of minute particles is
approximately 0.1mm or less.
• While both diffusion and screening are suitable if they are between
0.1mm and 0.5mm.
• Inertial collision and screening are effective for particles of 0.5mm or
more.

27. Continue…..
• As for collection of the particulate matter, diffusion is effective for
minute particles
• While inertial collision, screening and gravity are effective for larger
particles of about 2mm or more.
• Selection of the filter paper depends on the characteristics of the matter
to be measured and the method of analysis
• Two types of filter paper for collecting particulate matter
 Fabric
 Porous membrane filters

28. Weighing of filter paper
• Weigh the collection filter paper before and after use with a direct reading balance
with a sensitivity of 0.1mg or greater
• After leaving it in a balance room with fixed temperature and humidity for 24 hours
• Great care must be taken when weighing and handling the filter paper
• Easily damaged
• Weigh each sample at least twice and confirm that such readings are nearly identical
• If they differ substantially, repeat the weighing procedure until stable values are
obtained

29. Storing collection filter papers
• The storage method for filter paper that has been used for collection differs
depending on the analysis objectives
• Heavy metal components can be stored at room temperature after being placed in
a plastic bag or suchlike to avoid contamination from within the room
• Anionic or organic components are very volatile and easily deteriorate at room
temperature, so they need to be kept refrigerated or frozen.
• There are some substances whose concentration certainly decreases under light at
room temperature
 Benzopyrene

30. Balance
(1)Points to note when setting up the balance
• It is preferable to place the balance in an exclusive room such as a balance room
• If there is no balance room, it should be placed somewhere that is used by few
people and where the room temperature is stable
• The balance should not be placed anywhere that is at all unstable or shakable
• It should not be placed near a heat source such as a heater or in direct sunlight

31. (2) Points to note on usage
• When using a balance, maintain an upright posture and do not place your elbows on
the balance table
• Do not get too close to the balance either because the more minute the balance
reading is, the more easily its zero point is affected by human body temperature
• Turn the operation handle very gently to make operating status of the balance
• When weighing a hygroscopic sample, it is best to weigh it after operation of the
balance is settled

32. By Laiba Shaheen
21011561-002
32

33. Sampling Gaseous Matter
• When sampling air, sampling vessels are selected in accordance of objectives
• Air pollution are always found in constant concentration
• Vary with time
• To conduct air sampling over a longer period to obtain the average concentration
at that site
• Natural ventilation method
• Open the mouth of the sampling vessel
• fix it at the measurement point and wait for air to enter the vessel in accordance
with the natural ventilation.

34. Continue.....
• Close the mouth to retain the sample
• Average concentration within the time range at the measurement point can be
obtained
• Not such an accurate method
• Vacuum vessel method
• Vacuum the sample vessel before collection
• Sampling can be done by simply opening the valve at the collection point
• Suitable for situations where ‘instant’ sampling is required

35. Sampling Method on the dynamic flow
• Suck out the air from one sampling hole on the vessel using an air pump at the
measurement site
• To Introduce the sample gas through another sampling hole
• This is the optimal method for air sampling
• One considers time and sample gas
• Displacement method
• Place a bag within a vessel and introduce and expel the air sample to/from the bag
by removing
• Refilling the gas in the vessel outside the bag

36. Continue.....
• Advantages
• Air sample within the bag can easily be emitted and reintroduced
• The bag material must be selected with due consideration for the component to be
measured
• Concentrating methods
Adsorption method
Adsorbs and collects matter including the targeted components by ventilating the
sample gas
• Through tube filled with adsorbent. Activated carbon, silica gel, molecular sieve,
alumina, and backing
• For gas chromatographs are used as the adsorbents

37. Continue.....
Low temperature concentrating method
• Insert the sampling tube into a vessel cooled by a coolant
• To make use of the principle that components of higher concentration than the
vapour pressure of Coolant components collected
• The efficiency for collecting the targeted components relies
• On difference between the sample concentration and the vapour pressure value at
the temperature of said component
• The absorption rate
• Degree of diffusion to the collected

38. Continue.....
• Shape of the trap
• Gas flow rate
• Absorbent reaction method
• DNPH method, which is used to measure aldehyde within the air
• Reaction solution absorption method
• Put a suitable reaction absorption solvent for the targeted component into an
impinger
• Sample the gaseous matter in the air at a constant suction flow rate

39. By Mariyam Shehzadi
•21011561-
007

40. Air sampling techniques for gaseous
pollutants
• ABSORPTION SAMPLING
•
• ADSORPTION SAMPLING
•
• CONDENSATION SAMPLING

41. ABSORPTION
SAMPLING
➢ Gaseous pollutants are absorbed in a solvent when both the
pollutant and absorbent are in close contact
➢ Liquid react with the gaseous pollutant to form a non
gaseous pollutant
✓ ALKALINE FOR ACIDIC GASES
✓ ACIDIC SOLUTION FOR ALKALINE GASES
✓ OILS FOR HYDROCARBONS

43. ➢ Gaseous pollutants are adsorbed on the solid
surface of activated carbon, silica gel, activated
alumina and molecular sieve
➢ As the surface area increases the adsorption
increases
ADSORPTION SAMPLING

45. CONDENSATION
SAMPLING
• The conversion of a vapour or gas to a liquid
• Method used to collect the radioactive gases,
hydrocarbons and non reactive vapors
• Air pollutant can be trapped by condensation reaction
• As the gaseous pollutant pass through the different
temperature range of condensers where the temperature
is below the boiling point the gaseous pollutant will trap
in the liquid

47. SOME NEW METHODS OF AIR SAMPLING
Bubble Sampling
➢ Air drawn into the impinger is forced through a nozzle, which is covered by a
liquid such as high purity water.
➢ The pollutant dissolves in the liquid and is subsequently analysed, usually by
colorimetric techniques.
Sorbent Sampling
➢ Sorbents are normally contained in a small glass tube with sealed ends.
➢ Air is drawn through the sorbent, which captures molecules of the gas or
vapour to be sampled.
➢ The trapped contaminants are released using solvent washing or heat to a gas
chromatograph (GC) for analysis. One of the best known sorbents is charcoal.

48. THANK YOU