Ambient Air Quality Monitoring Methods

Lydia Scheer ITEP

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What will we learn?

Reasons for monitoring ambient air quality Methods available for different pollutants

and/or parameters Considerations for air monitoring National and regional issues related to air

monitoring

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Why Monitor Air Quality? Examine and characterize airshed

Health or environmental effects Cultural reasons Political issues Economic or land-use planning

Gauge compliance with standards/regulations NAAQS attainment or non-attainment

EPA Green Book lists NA areas (www.epa.gov/airquality/greenbk/) Non-attainment: progress toward attainment What control/prevention strategies are needed? Are they

working?

Why is your tribe monitoring? Answering this question will help to determine your air

monitoring objectives

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Evaluating Impacts

Think about monitoring objectives—why are you monitoring? Consider impacts at both the receptor and the source

What is the level at source? What are downwind/upwind levels? What areas are most impacted and/or what areas are you

concerned about? (receptors) Establish baseline data representative of your area Determine maximum, average pollutant concentrations Will you be issuing health alerts or monitoring trends?

Are you meeting your objectives?

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Network Considerations

“Network” can be a single site or multiple sites Monitoring objectives Meteorology & pollutant/precursor transport Monitoring schedule Site requirements, access and security, long-term

viability NAAQS monitoring: 40 CFR Part 58 Appendix E Met monitoring: EPA-454/R-99-005 Special projects often have their own specific

requirements

Necessary to review and modify network based on objectives and changes to surrounding conditions

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Equipment Considerations

Monitors/samplers & sensors FRM or FEM or not?

Must be FRM/FEM in order to compare to NAAQS (40CFR Part 53) Collocation requirements for some types of monitoring

Ancillary equipment Dataloggers QA/QC equipment incl. flow meters, transfer standards,

calibrators, etc. Consumables

Grease/oil Filters/filter tape

Concrete pad and shelter Electricity requirements A/C or heating needs

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Regulatory Considerations

To officially compare to the NAAQS (for attainment designations or compliance) you MUST follow all requirements outlined in 40CFR Part 58

All EPA-funded projects involving data collection require approved QAPP

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Pollutants & Parameters Criteria pollutants

Particulates PM10 (particulate matter < 10 mm) PM2.5 (particulate matter < 2.5 mm)

Ozone Lead SO2 NOx CO

Air Toxics (HAPs) and/or VOCs Meteorological parameters Acid & Mercury deposition

Particle Sizes

Human Hair (~70 µm diameter)

PM2.5

(2.5 µm)PM10

(10µm)

Cross Section: (~70 µm)

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PM Filter-Based Samplers

HiVol (TSP or PM10 only), MiniVol, Partisol, others

Most HiVols & Partisols are FRM or FEM (epa.gov/ttn)

24-hour sample collected onto filter Single channel or sequential option for Partisol Filter mass weighed by lab to determine

average ambient concentration Samples can be analyzed further for

constituents (speciation)

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Filter-Based Pros & Cons

Filter-based equipment demands more resources Personnel/time Filters & other consumables Laboratory analysis is costly

Less expensive to purchase than continuous samplers

Data are not “real-time” MiniVols are more portable than larger equipment

MiniVol is not FRM or FEM MiniVol can sample PM10 or PM2.5 MiniVol data is not legally-defensible

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R&P PM2.5 Partisol FRM

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HiVol & MiniVol

                                                      

14Credit: www.rpco.com

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Filters

47mm Teflon-coated Glass (PM2.5 or PM10)

47mm Quartz Fiber or pure Teflon (used for speciation)

8” x 10” Glass Fiber (PM10 HiVol) Also specialized filters for some models

See examples

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Continuous PM Monitors

Examples: TEOM, BAM, Nephelometer (some applications)

Collect samples “continuously” (readouts vary from every 5 minutes to every 1 hour)

Particles collected on filter tape or pad and weight (mass) is analyzed internally

Can be used for PM10 or PM2.5

Several models are FEM

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TEOM & BAM

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Continuous Pros & Cons

Provides data in “real-time” Continuous equipment is more

costly/fragile Automated readings and no filters means

minimized personnel time & lab costs Some consumables and maintenance Needs constantly reliable power source &

adequate shelter Requires Datalogger/DAS

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Dataloggers/DAS

Electric or electronic computing devices that record measurements from other instruments

Various programming requirements and configurations

Datalogger input connection must match sensor output connection

Helpful to understand basic electricity concepts for troubleshooting

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Datalogger Characteristics

Analog Transmits voltage reading, translated into pollutant

concentration or other parameter Typically linear relationship between outputs and

readings enables logging values anywhere within the range

“Noise” in analog connections can introduce error Digital

Transmits specific values for pollutant concentration or other parameters

Values can increase or decrease only at specific, discrete intervals and not between intervals

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Gaseous Monitoring Methods

“Passive” sampling Often a chemical reaction involved, end

sample is analyzed Spectrophotometry and UV Photometry

Measures amount of light a sample absorbs Primarily used for SO2 & Ozone

Chemiluminescence Chemical reactions gives off light of a certain

color Used for O3, NOx, SOx and H2S

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Sampling Equipment- Gaseous Pollutants

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Air Toxics/HAPs

187 Hazardous Air Pollutants (HAPs) Volatile & semi-volatile organic vapors

e.g., benzene, dioxin, formaldehyde, etc.

Heavy-metal dust, aerosols & vapors e.g., mercury, nickel, antimony, etc.

Inorganic & mineral dust, aerosols & vapors

e.g., arsenic, asbestos, etc.

Radionuclides Including radon

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Sampling Methods - HAPs

Multiple methods depending on pollutant and emission process

Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air (Method TO-1, etc.)

Compendium of Methods for the Determination of Inorganic Compounds in Ambient Air (Method IO-1, etc.)

Photo courtesy of Frank BlackCloud, Spirit Lake Tribe

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Meteorological Monitoring

Can be conducted along with ambient air monitoring Helps to identify where pollution is coming from

and/or where its impacts are greatest Some ambient air samplers & dataloggers can record

limited met data Meteorological parameters to consider

Wind speed (how far?) Wind direction (where/what direction?) Temperature (affects aerosolization of particles) Barometric pressure (impacts atmospheric conditions

affecting transport) Relative humidity (affects aerosolization of particles) Solar radiation (affects formation of ozone)

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TOWERS

WIND SENSORS

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Atmospheric Deposition

Wet Deposition (“Acid Rain”) Monitored by National Atmospheric Deposition Program

(NADP) Acid deposition occurs when pollutants (primarily SOx or

NOx) react in atmosphere with water vapor & returns to earth as precipitation (rain, snow, fog)

Measurements are made for pH and conductivity and precipitation

Dry Deposition Monitored by the Clean Air Status & Trends Network

(CASTNET) Occurs when pollutants react, but not with water Pollutants settle out of atmosphere as particles or gases

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Mercury Deposition

Mercury Deposition Network part of NADP analyzes mercury samples from wet deposition monitoring

Monitoring for elemental and inorganic mercury conducted at the source

Organic mercury (methylmercury) samples can also be collected from environmental receptors Aquatic and other wildlife Wetlands/waterways Sediments

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Typical NADP Site

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What We Just Covered

Ambient air pollution can be monitored, sampled and/or analyzed in numerous ways

Sampling types include filter-based, continuous, passive and chemical-based methods

All monitoring methods have pros and cons

Monitoring may or may not be important to meet certain needs of an air program

EPA regularly revises NAAQS standards