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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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Criteria Pollutants

• 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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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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Chemistry of Ozone

VOCs + NOx + Sunlight + Heat = Ozone

Night Time O3 Chemistry

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Ambient Air Standard-Ozone

• To attain the ozone NAAQS, the 3-year average of the annual 4th-highest 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 The 4th highest 8-hour average is:

75

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

This would average to 88

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Schematic Diagram Ozone Monitor

Photodiode

Air PumpThermistor

Hg Lamp

254nm

Solenoid Valve

Ozone

Scrubber

Pressure Sensor

Air Inlet

Absorption Cell

Ozone Monitors

Rack mount with ozone transfer standard instrument and ozone monitor.

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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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Chemiluminescence

The chemiluminescence reaction of NO to NO2:

NO + O3 ==> NO2+ O2 + hv

Variations of chemiluminescence have been used to perfom measurements of Ammonia (NH3): NH3 + O2 ==> NO + H2Oor:4NH3 + 5O2 = 4NO + 6H2Othen: 4NO + 4O3 -------->4NO2+4O2 + 4hv

http://www.k2bw.com/chemiluminescence.htm

Schematic of a reaction chamber under vacuum and aPhotomultiplier 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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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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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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TEOM 1400 Ambient PM Sampler

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Meteorological Parameters

• 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/FAQ-uvrad/faq4.html

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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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Air Monitoring Sites-Texas

Typical Site

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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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GC-MS Analytical System

Gas Chromatograph

Pre-concentrator

Mass SpectrometerSample Canister

ANALYSIS AND

COLLECTION OF DATA

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Automated Data Collection

Databases

• 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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Ozone Concentrations vs Wind

Time Series Graph

September 29, 2004

0

20

40

60

80

100

120

1 3 5 7 9 11 13 15 17 19 21 23

Time

Ozo

ne-

pp

b

AP HR VI CAMS04 CAMS21 Kingsville

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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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Pollution Rose

• Can be used for

evaluating the

common direction of

pollutants

• Useful for ozone, PM,

SO2, VOCs.

Direction of Sources

• 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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Air Parcel Trajectories

REFERENCES

• 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-Handbook-

Vol-II.pdf