Toxic Air Pollutants: Air Pollution Monitoring Advances

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Toxic Air Pollutants Air Pollution Monitoring
Advances
Dr.Rakesh Kumar NEERI
IAAPC, September 23 2007
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CLASSIFICATIONS CHANGING

• PHYSICAL DUST
• CHEMICAL SOLVENTS
• BIOLOGICAL SPORES/VIRUSES
• OTHERS HEAT .SWEAT??

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ANALYSIS STYLE CHANGING PM

• SMOKE VISIBILITY STILL USED IN MANY COUNTRIES
  INCLUDING USA
• MASS BASIS MOST COMMON But debated most about
  its validity in last 5-8 years
• PARTICLE PHYSICAL CHARACTERISTICS
• PARTICLE CHEMICAL CHARACTERISTICS
• PARTICLE BIOLOGICAL CHARACTERISTICS
• PARTICLE MAGNETIC PROPERTIES
• PARTICLE SIZES AND CHEMICAL AND PHYSICAL AND .

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ALL THESE GIVING US MORE AND MORE INSIGHT INTO
NEW PM PROBLEMS ITS ALSO GIVING CHALLNGES FOR
MONITORING AND MAKING STANDARDSITS GIVING
COMPLEXITY IN CONTROL MECHANISMS
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COMPLEXITIES OF MASS AND SIZES CASE OF ONE SITE
IN MUMBAI VEHICLE

• SPM of 365 ug/m3 PM contribution of 4
• PM10 of 200 ug/m3 PM contribution of 20
• PM2.5 of 128 ug/m3 PM contribution of 43
• PM1.0 of 33 ug/m3 PM contribution of 79

Shifting from diesel to CNG helps in reducing SPM
to some extent and more in PM10 and PM 2.5 If we
get into particle numbers we would have
increased particle 10 folds
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COMPLEXITIES OF CHEMICAL ANALYSIS

• Highly variable for sites, seasons and
  continents.
• Inorganics Europe 17 to 55,
• Indian SC 25 to 80
• Total Carbon Europe 15-40
• USA 23-35
• Asia (Ind) 22-63
  
• Long range transport contributions About 40-70
  of PM2.5 in Finland
• In India, Pakistan, Bangladesh probably in
  similar or higher range

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Chemical Composition Complexities

• In the USA, the PM2.5 fraction has far lower
  sulphate concentrations and higher elemental and
  organic carbon concentrations in the Western US
  than in the Eastern US.
• Also in the eastern US, Sulphate far exceeds
  nitrate, whilst in the western US, nitrate
  predominates.
• Percentage of EC and OC in Latin America are in
  the range of 11 and 40 respectively and Crustal
  components were found to be in the range of 8 to
  24.
• In Asian countries, EC ranges between 7 in
  Hongkong and 16.25 in and Kolkotta, India.
• The percentage organic composition was 7.9
  lowest at Sado island and highest 62 at valley
  site in Nepal.
• Sulphate composition was highest in Taiwan with
  48.85 and minimum in Delhi with 8.3.

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Chemical Composition Complexities

• In the USA, the PM2.5 fraction has far lower
  sulphate concentrations and higher elemental and
  organic carbon concentrations in the Western US
  than in the Eastern US.
• Also in the eastern US, Sulphate far exceeds
  nitrate, whilst in the western US, nitrate
  predominates.
• Percentage of EC and OC in Latin America are in
  the range of 11 and 40 respectively and Crustal
  components were found to be in the range of 8 to
  24.
• In Asian countries, EC ranges between 7 in
  Hongkong and 16.25 in and Kolkota, India.
• The percentage organic composition was 7.9
  lowest at Sado island and highest 62 at valley
  site in Nepal.
• Sulphate composition was highest in Taiwan with
  48.85 and minimum in Delhi with 8.3.

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Complexities of markers

• COOKING RANGES CAN INCREASE NO2 CONCENTRATIONS
  INDOORS and add 2-40 different kind of HC
• CIGARETTE SMOKE CONTAINS MORE THAN 4000
  SUBSTANCES, MORE THAN 40 OF WHICH ARE KNOWN
  CARCINOGENIC AGENTS
• INDOOR ETS CAN BE FATAL EVEN WITH SHORT TERM
  EXPOSURE WITH SO MANY KNOWN AND UNKNOWN COMPOUNDS

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SOURCE COMPLEXITIES INDOOR VIS A VIS OUTDOOR

• HOUSEHOLD CLEANING AND MAINTENANCE COMPOUNDS
• SOURCES OF MORE THAN 100 POTENTIALLY HARMFUL
  CHEMICALS

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Source and Receptor Models
Known Source Emissions
Source Model
Estimated Ambient Concentrations
Known Dispersion Characteristics
Source Models
Known Ambient Concentrations
Estimated Source Impacts
Receptor Model
Receptor Models
Attempts in modelling complete mass balance
difficult with limited data All accounting in
model Not worth most of the time
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Apportionment Issues

• Some of the research attempts have been able to
  get the information with simple technique
• Receptor models commonly used are Chemical Mass
  Balance, Principal component analysis, Factor
  analysis, Positive Matrix Factorization and
  Multiple Linear regression. All claiming to be
  good
• In urban areas, complexities due to multiple
  small sources make interpretation difficult with
  limited data

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Gaps

• For any attempt of newer standrads on fine
  particles, India needs to establish a credible
  data sets for a longer period with
  epidemiological studies especially in developing
  countries..
• Mass and Number criteria will need to be
  addressed sooner. Some of these are highly linked
  with visibility.
• Indoor air exposure and its burden in changing
  outdoor would be the most significant information
  for long term policy decisions.
• Limited information on background particulate
  concentration or characteristics of fine
  particles in background areas.
• All monitoring sites located in urban regions
  except some research sites for background. More
  background sites for fine particle transport
  related information.

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Gaps

• Secondary aerosol will be critical in coming
  times when we go for fine particle measurements.
• Geographical dependence of fine aerosol
  properties, aerosol loading, rates of formation
  and removal, dilution and transport
• Strongly bound water is an important component of
  fine aerosol. Water influences physico-chemical
  parameters like size and light scattering. There
  is a gap in understanding the uptake of water
  content by the hygroscopic aerosol components.
  Tools are required to assess the water content of
  PM2.5 aerosol.

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Research Implications

• Its important to know which fraction of the PM
  can not be handled and addressed. Therefore, more
  debate needed.
• Sampling and analysis of PM2.5 is most important
  area of research because without accurate
  measurement and speciation of fine particles,
  source apportionment and dose-response studies
  will not be valid.
• Identifying important species in PM2.5 will help
  in suggesting control strategies.
• The findings will assist the researcher and the
  gaps identified in current knowledge could be
  addressed in future research.

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MONITORING ISSUES

• ALL KINDS
• SPM
• PM10
• PM 2.5
• PM 1
• ULTRA-FINES

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Instruments used in PM Sampling

• Advance instrument
• Speciation
• Mass concentration
• Number concentration
• Size fractionation
• Configuration measurements
• Mobility and aggregation

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NEED FOR Precursor Gas Particle Monitoring
Progress in science and technology to address
complexity
Need precursors to support research data uses and
the general support of atmospheric sciences
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NEW AREAS OF DEVELOPMENT

• New concepts being applied and being used quickly
  in the field
• Need to understand and integrate to use for
  policy implementation
• New groups to join and work towards the same

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Profile Trace Gas Analyser

• Applications for trace gas measurement are varied
  and challenging and growing in number every day.
  Quantitative analysis of real samples has always
  been a problem, particularly moist samples, such
  as exhaled breath.
• The profile, from Instrument Science, provides
  solutions not available elsewhere. Gas phase
  samples can be analysed down to single digit ppb
  levels, without pre-concentration. The breath
  from a patient, the atmosphere in a workplace or
  the exhaust from an engine can be sampled
  directly, providing immediate results.
• Volatile liquids can also be analysed via their
  headspace.
• It uses SIFT-MS (Selected Ion Flow Tube Mass
  Spectrometry) , which are redefining the state of
  the art in trace gas analysis. These systems have
  been designed to be transportable, have moderate
  power requirements, require minimal consumables
  and be cost effective.

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• Technique
• SIFT-MS (Selected Ion Flow Tube Mass
  Spectrometry) uses chemical ionisation, gas phase
  ion chemistry and quantitative mass spectrometry.
  
• In full scan mode, the spectrum of all ions
  across a chosen mass range is available. This
  allows unusual peaks to be recognised and
  identified.Profile for routine analysis
• Some of the very common kind of compounds which
  can be analysed
• alcohols
• aldehydes
• alkanes
• alkenes
• ammonia
• aromatics
• cyanides
• esters
• ethers
• ketones
• organosulphur compounds
• ......and more

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Real-Time Monitoring of Dioxins and Other Ambient
Air Trace Organics
The Resonance Enhanced Multi Photon Ionization
(REMPI) instrumental method is a tool that will
be used for assessment of potential dioxin
sources, control and prevention of dioxin
formation in known sources, and communication of
facility performance.
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Relevant concentrations of these compounds are
often in the parts per quadrillion levels and
become even lower as emissions become cleaner.
Therefore, it is important to search for
compounds which are spectroscopically viable, are
more abundant, and/or are more easily detected,
such as dioxin formation precursors and
chemically-related dioxins and furans which serve
as indicators of the presence of the full range
of toxic 2,3,7,8-Cl-substituted compounds.
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Progress of Air Monitoring Techniques

• Until the 1970s the most common methods of air
  quality monitoring involved bubbling air through
  a reagent solution using a so-called absorption
  train. The pollutant dissolves in the reagent
  solution and is subsequently analysed in the
  laboratory, usually by UV-vis spectrophotometry.
  Problems of interference and some limited
  pollutnats (eg SO2, NO2, O3). But these methods
  are still recognized methods as references
  against which all other (including instrumental)
  methods are compared.
• Instruments capable of providing a continuous
  record of air pollution appeared in the 1970s and
  were generally based on spectroscopy (UV-vis and
  IR). Point measurement
• Instrumental methods greatly increased the range
  of pollutants for monitoring using fully
  automated AQMSs. Almost real time CO by
  non-dispersive infrared (NDIR) spectroscopy, O3
  by UV absorption spectroscopy, SO2 by UV
  fluorescence spectroscopy, and NOx by
  chemiluminescence. Can measure concentrations as
  low as 1ppb, with very fast response times
  (seconds to minutes).
• Highly automated and networked for better
  management.
• .

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Open-path methods

• During the 1990s, a novel approach to air quality
  monitoring using spectroscopy - known as
  open-path methods - gained ground.
• Instead of measuring pollution at a specific
  location, open-path methods record the average
  pollutant concentration along the path length of
  a light beam. Measurements are made in situ and
  there is no disturbance in the air flow due to
  pump sampling as with point analysers.
• Open-path methods are used for the remote sensing
  of the atmosphere and provide better estimates of
  average pollutant concentrations over a given
  area. A single instrument can measure several
  components, both organic and inorganic.

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• Currently, there are gt 1000 users of open-path
  systems worldwide and this number is steadily
  growing. Open-path systems1 include
• Differential Optical Absorption Spectroscopy
  (DOAS),
• Fourier Transform Infrared Spectroscopy (FTIR),
• Light Detection and Ranging (Lidar),
• Differential Absorption Lidar (Dial),
• Tunable Diode Laser Spectroscopy (TDLAS).
• DOAS is the most widely applied open-path method
  used for air quality monitoring. FTIR is another
  commonly used open-path technique.

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• The DOAS method has the advantage of superior
  detection limits (lt1ppb).
• DOAS can be used for monitoring SO2, NO, NO2, O3,
  CO2, HCl, HF, NH3, CS2, Cl2, HNO2 and many
  organic compounds (aldehydes, phenol, benzene,
  toluene, xylenes, styrene, cresol).
• In addition, DOAS has been used to measure low
  concentrations of unstable radicals such as OH
  (106-107 molecules cm-3) and NO3 (107-1010
  molecules cm-3).

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Optical radar

• The Lidar method advances open-path remote
  sensing technology even further.
• Lidar is essentially the optical equivalent of
  radar, using a laser as the light emitter. Due to
  the short wavelengths of laser light, Lidar can
  be used to determine concentrations of suspended
  particles, aerosols, and gases.
• Lidar uses a pulsating laser source and signals
  backscattered by molecules and particles are
  analysed using a specially designed telescope.
• The optical path can be up to 250 km long. By
  rotating Lidar in space it is possible to
  determine the spatial distribution of air
  pollution over a large area.
• .

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Conclusions

• Some of the advancement of PM and Fine PM need to
  be looked at comprehensively.
• Health, meteorological, chemical, biological,
  magnetic.. All fields to be linked
• Good advancement in air quality monitoring has
  taken place due to need
• Its becoming more complex but more accurate
• Though expensive but low operating costs
• Challenges of Indian conditions and adaptations
• Demand driven indigenous development

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• Thanks