The Role of Monitoring Networks

in the Management of the Nation's

Air Quality

National Science and Technology Council

Committee on Environment and Natural Resources

Air Quality Research Subcommittee
About the National Science and Technology Council

President Clinton established the National Science and Technology Council (NSTC) by Executive Orde

on November 23, 1993. This cabinet-level council is the principal means for the President to coordinat

science, space, and technology policies across the Federal Government. The NSTC acts as a “virtual

agency for science and technology to coordinate the diverse parts of the Federal research an

development enterprise. The NSTC is chaired by the President. Membership consists of the Vice

President, the Assistant to the President for Science and Technology, Cabinet Secretaries and Agenc

Heads with significant science and technology responsibilities, and other White House officials.

An important objective of the NSTC is the establishment of clear national goals for Federal science an

technology investments in areas ranging from information technology and health research, to improvin

transportation systems and strengthening fundamental research. The Council prepares research an

development strategies that are coordinated across Federal agencies to form an investment package tha

is aimed at accomplishing multiple national goals.

To obtain additional information regarding the NSTC, contact the NSTC Office of the Executive

Secretary at (202) 456-6100.

On-line information is at http://www.whitehouse.gov/WH/EOP/OSTP/NSTC

About the Office of Science and Technology Policy

The Office of Science and Technology Policy (OSTP) was established by the National Science an

Technology Policy, Organization and Priorities Act of 1976. OSTP’s responsibilities include advisin

the President on policy formulation and budget development on all questions in which science an

technology are important elements; articulating the President’s science and technology policies an

programs; and fostering strong partnerships among Federal, State, and local governments, and th

scientific communities in industry and academia.

To obtain additional information regarding OSTP, please contact the OSTP Administrative Office at

(202) 395-7347.

On-line information is at http://www.whitehouse.gov/OSTP

About the Committee on Environment and Natural Resources

The Committee on Environment and Natural Resources (CENR) is one of five committees under th

NSTC and is charged with improving coordination among Federal agencies involved in environmenta

and natural resources research and development, establishing a strong link between science and policy

and developing a Federal environment and natural resources research and development strategy tha

responds to national and international issues.

To obtain additional information about the CENR, contact the CENR Executive Secretary at

(202) 482-5181.

On-line information is a http://www.nhic.noaa.gov/CENR/cenr.html

Committee on Environment and Natural Resources

D. James Baker, Co-Chair

National Oceanic and Atmospheric Administration

Rosina Bierbaum, Co-Chair

Office of Science and Technology Policy

Terrance Flannery

Central Intelligence Agency

John Lieber

Department of Transportation

Kathleen McGinty

Council on Environmental Quality

Lawrence Reiter (Acting)

Environmental Protection Agency

Eileen Kennedy

Department of Agriculture

Craig Wingo

Federal Emergency Management Agency

Sherri Goodman

Department of Defense

Ghassem Asrar

National Aeronautics and Space Administrat

Martha Krebs

Department of Energy

Joseph Bordogna

National Science Foundation

Kenneth Olden

Department of Health and Human Services

Samuel Williamson

Office of the Coordinator for Meteorology

Mark Schaefer

Department of the Interior

T.J. Glauthier

Office of Management and Budget

Roland Droitsch

Department of Labor

Thomas Lovejoy

Smithsonian Institute

Melinda L. Kimble

Department of State

Kathryn Jackson

Tennessee Valley Authority

Subcommittees

Air Quality Research

Martha Krebs, DOE, Chair

Dan Albritton, NOAA, Vice Chair

Robert Perciasepe, EPA, Vice Chair

Natural Disaster Reduction

Bill Hooke, NOAA, Chair

John Filson, USGS, Vice Chair

Craig Wingo, FEMA, Vice Chair

Ecological Systems

Mark Schaefer, DOI, Chair

Mary Clutter, NSF, Vice Chair

Donald Scavia, NOAA, Vice Chair

Toxics and Risk

Lynn Goldman, EPA, Chair

Kenneth Olden, NIEHS, Vice Chair

Anna Johnson-Winegar, DOD, Vice Chair

Global Change Research

Robert W. Corell, NSF, Chair

Ghassem Asrar, NASA, Vice Chair

Mike Dombeck, USDA, Vice Chair
1

Air Quality Research Subcommittee

Chair Martha Krebs, DOE

Vice Chair Daniel Albritton, NOAA

Vice Chair Robert Perciasepe, EPA

White House Liaison Frances Sharples, OSTP

MEMBER DEPARTMENTS AND AGENCIES

Department of Agriculture

Department of Energy

Department of Health and Human Services

Department of Housing and Urban Development

Department of State

Department of the Interior

Department of Transportation

Environmental Protection Agency

National Aeronautics and Space Administration

National Oceanic and Atmospheric Administration

National Science Foundation

Office of Management and Budget

Office of Science and Technology Policy

Tennessee Valley Authority
CONTENTS

Introduction...................................................................................................

Why monitor?................................................................................................

Current Air-Quality Monitoring Networks and the Pollutants Monitored....

IMPROVE......................................................................................................

SLAMS/NAMS ...............................................................................................

PAMS.............................................................................................................

NADP/NTN ...................................................................................................

NADP/MDN ..................................................................................................

CASTNet........................................................................................................

AIRMoN ........................................................................................................

Gaseous Pollutant Monitoring Program (GPMP)........................................

How Important is the Current Monitoring Infrastructure in Addressing

Emerging Issues?.......................................................................................

The Role of the Committee on the Environment and Natural Resources,

Air Quality Research Subcommittee..........................................................
INTROD

Prevailing

Winds

Photochemistry

Cloud Processes

Chemical Transformations

Fire

Ground Water

Drinking Water

Aquatic

Ecosystem

Cultura

Resourc

Human

Health

Agricultu

 Produc

Soils

Visib

Lightning

Agriculture Industry

Wet Deposition Dry Deposition

Dispe

Vertical

Mixing

Sources Transport / Transformation Removal

Effects

Forest

 Productivity

Transportation

Ocean

The Role of Monitoring Networks

in the Management of the Nation’s

Air Quality

National Science and Technology Council

Committee on Environment and Natural Resources

Air Quality Research Subcommittee

INTRODUCTION

Nearly three decades ago, the country responded

to growing concerns over the quality of the air in the

United States by adopting the landmark Clean Air Act

in 1970. This Act established two types of national airquality standards. Primary standards set limits to

protect public health, and secondary air quality standards were set to protect public welfare, including

protection against decreased visibility and damage to

animals, crops, vegetation, and buildings. In the mid1970’s, there was growing awareness in the United

States of the linkages found in Europe between air

quality and impacts to aquatic and forest ecosystems.

This awareness led to concern that atmospheric emissions and subsequent atmospheric deposition could be

causing similar problems in the United States. In the

1977 amendments to the Clean Air Act, Congress

established as a national goal the remediatio

existing impairment in visibility resulting fr

pollution in National Parks and Wilderness 

the prevention of any future degradation in t

The Clean Air Act Amendments of 19

(CAAA) built upon the original Act in initia

expanding programs to address acid rain and 

pollution, and identified 189 "toxic" air poll

regulation. Air toxics are those pollutants th

known or suspected to cause cancer, serious 

developmental defects, or other adverse hea

impacts. The Amendments also established 

permits program to make the law more work

an improved enforcement program to help e

better compliance with the Act. The new law 

encouraged the use of market-based princip

other innovative approaches, like performan

standards and emission banking and trading

Air Pollution: Sources, Transport, Transformations, Removal, and Effects
2 The Role of Monitoring Networks in the Management of the Nation’s Air Quality

Why monitor?

“Air quality is the best it’s been in 30 years.”

“Air quality in our wilderness areas is declining.”

Conflicting headlines such as these and the often

emotion-driven opinions that surround most environmental issues confound the emergence of a clear

picture of what is happening to the quality of the air

we breathe and depend on for a healthy environment.

Long-term networks that monitor the levels of pollutants in the atmosphere provide important information

to scientists and policymakers regarding the current

status of the chemical composition of and deposition

from the atmosphere and how levels of pollutants

differ over time and space; these networks also

provide needed “hard data” for policy decisions.

Long-term changes in air quality and atmospheric deposition can be obscured by the large dayto-day, season-to-season, and year-to-year variations

in winds, temperature, precipitation, and atmospheric

circulation patterns that in turn affect dispersion, transport, and deposition of pollution. In order to see the

larger picture, beyond these shorter term variations, it

is important to monitor for long periods of time, using

consistent procedures and quality-assurance practices

to observe long-term and significant changes in atmospheric composition.

Air-quality monitoring networks provide a vital

performance measure to aid in determining and

reporting how effective current regulations are in

improving air quality as required under the Government Performance and Results Act (GPRA) and

provide the data needed to revise existing or promu

gate new regulations. For example, cumulative inves

ments in environmental controls by major United

States power utilities are estimated at $63 billion

through 1994, representing 12% of electric utility

plant investments. These costs are passed on to the

public in the form of higher costs for energy, transpo

tation, and other goods and services. The Nation’s a

quality monitoring networks provide the only nation

wide basis to determine if these actions are providin

the desired benefits, namely an improvement in air

quality and a reduction in the adverse environmental

impacts to our land and water resources from atmospheric deposition. Market-based incentives provide

in the CAAA, such as emission trading, banking of

emission reductions, and allowing industry to select

the most cost-effective means for reducing emission

are revolutionary in nature. Proposals are under

consideration that would extend the use of these mec

anisms as an alternative approach to more traditiona

regulatory actions. The air-quality networks provide 

mechanism for determining the effectiveness of thes

new regulatory approaches in protecting the environ

ment.
CURRENT AIR-QUALITY MONITORING NETWORKS AND THE POLLUTANTS MONIT

CURRENT AIR-QUALITY MONITORING

NETWORKS AND THE POLLUTANTS

MONITORED

Eight federally supported, national air-quality

monitoring networks are operating currently in the

United States. Other specialized regional and local

research networks exist primarily to address local

environmental issues. The following matrix 

the monitoring networks to the measured atm

chemical constituents or properties. As many 

10 chemical constituents in atmospheric depo

measured by the deposition networks. Each 

existing networks described in this report uti

extensive quality-assurance practices and pr

so that comparable data are available for det

spatial and temporal trends in air quality.

Network Lead Federal

agency

Number

of sites

Estimated FY 99

Federal funding

(millions $)

Nonfederal

participation? Initia

IMPROVE NPS 108 $2.9 Yes 198

SLAMS/NAMS EPA 3,200 $114.0 Yes 197

PAMS EPA 83 $12.1 Yes 199

NADP/NTN USGS 215 $3.5 Yes 197

NADP/MDN None 36 * Yes 199

CASTNet EPA 80 $4.5 No 198

AIRMoN NOAA 23 $0.6 Yes 198

GPMP NPS 33 $1.5 Yes 198

*Total funding approximately $0.6M, nearly all from State and local sources.

Air-quality

network Visibility Nitrogenspecies

Sulfur

species Lead Particulatematter

Carbon

monoxide

Ozone

and/or

precursors

Atmos

depo

IMPROVE • •

SLAMS/NAMS** • • • • • •

PAMS • •

NADP/NTN* • 

NADP/MDN • wet 

CASTNet • • • • • • dry 

AIRMoN •• • dry 

GPMP • •

*Atmospheric deposition constituents (SO4, NO3-N, NH4-N, Ca, Mg, Na, K, pH, specific conductance, and PO4).

**All pollutants are not monitored at each SLAMS/NAMS site.
4 The Role of Monitoring Networks in the Management of the Nation’s Air Quality

IMPROVE

The Interagency Monitoring of Protected Visual

Environments (IMPROVE) is a collaborative monitoring program to establish present visibility levels and

trends and to identify sources of anthropogenic

impairment. The National Park Service and the U.S.

Environmental Protection Agency (USEPA) are the

lead funding agencies for the IMPROVE Network.

IMPROVE began with 20 long-term monitoring

sites in 1987, and currently is

expanding to encompass

108 sites in parks and wilderness areas across the Nation.

The instrumentation and monitoring protocols have been

adopted by organizations with

common interests in air quality

and, as a result, additional sites

are operated by individual

Federal, State, and local government agencies. Numerous additional sites are operated in

17 countries around the world.

Visibility is most often

thought of in terms of visual

range or the farthest distance a

person can see a landscape feature. However, visibility

is more than "how far" one can see; it also encompasses visual contrast—a measure of how well scenic

landscape features can be seen and appreciated. Visibility cannot be fully defined by a single parameter via

monitoring of only one atmospheric parameter. Rather,

the objective of visibility monitoring is to understand

the effect that various types of particles, lighting

conditions, and humidity have on the appearance of a

scene. Therefore, the IMPROVE Network: (1) photographically documents the appearance of the scene

under various levels of visibility, (2) optically record

the characteristics of the atmosphere, and (3) measur

the composition of visibility-reducing aerosols to he

identify the source type and source strength of particles and gaseous precursors to secondary particles.

One of the principal purposes of the IMPROVE

Network is to gather enough data in order to identify

sources of impairment on individual site, regional, an

national scales.

When recent visibility

data from monitoring network

are compared to estimates of

pre-industrial visibility, a

picture emerges of “what we a

missing” due to impaired visibility. While the estimated

natural mean visibility in the

Western United States is 110–

115 miles, the best current mea

visibility, at greater than 90

miles, is found only in the inn

mountain West and Great Basi

regions. Moving east or west

from this area, the visibility

decreases quite rapidly, to

approximately 10–20 miles

along the West Coast, and to

less than 10 miles in much of the Eastern United

States. The estimated natural mean visibility in the

Eastern United States is 60–80 miles. Relative

humidity does not, by itself, cause visibility to be

degraded. Some particles, especially sulfates and aer

sols with polar organic constituents, accumulate wat

and grow to the size (0.3-μm to 0.7-μm diameter) th

is very efficient at scattering light. Poor visibility in

the Eastern United States during the summer month

is, in part, a result of the combination of high concen

trations of these particles and high relative humidity

Figure 1. IMPROVE Network.

Additional information on the IMPROVE Network

is available via the Internet at

http://www2.nature.nps.gov/ard/vis/vishp.html
SLAMS

SLAMS/NAMS

Carbon monoxide (CO), lead, nitrogen dioxide

(NO2), ozone, particulate matter (PM-10 and PM-2.5),

and sulfur dioxide (SO2) are monitored through the

State and Local Air Monitoring Stations (SLAMS)

and National Air Monitoring Stations (NAMS).

Although most air-quality samples at SLAMS/NAMS

sites are collected in urban areas where air quality is

influenced primarily by local sources, some sites are

located away from urban areas in order to characterize

regional air quality.

The primary objectives of the SLAMS

Network are to:

• Judge compliance with ambient air-qualit

standards.

• Activate emergency control procedures th

or alleviate air-pollution episodes.

• Observe pollution trends throughout the r

including nonurban areas.

• Provide a data base for research on urban, 

and transportation planning; developme

evaluation of abatement strategies; and 

ment and validation of dispersion mode

AIR-QUALITY MONITORING AND HUMAN HEALTH

National Ambient Air Quality Standards (NAAQS) have been set for six air pollutants. Primary NAA

designed to protect public health, and secondary NAAQS are designed to protect the public welfare such 

crops, visibility, and materials. In addition, indexes have been established for NAAQS pollutants, at gra

levels above the NAAQS, which describe differing degrees of alert or emergency that warrant different l

responses, depending on daily pollution levels. At the time NAAQS are set, Federal Reference Methods 

established for measuring air concentrations of the pollutant to determine changes in air quality and co

ance with the standard. A network of roughly 5,000 air-monitoring sites distributed throughout the coun

located primarily in and around high population centers is maintained to monitor NAAQS attainment. T

network consists of federally supported SLAMS (State and local air monitoring stations) and NAMS (N

Air Monitoring Stations) as well as other State-supported Special Purpose Monitoring Stations (SPMS)

Figure 2. State and Local Air Monitoring Network.

Figure 3. National Air Monitoring Network.
6 The Role of Monitoring Networks in the Management of the Nation’s Air Quality

Data from SLAMS/NAMS indicate air concentrations of lead, CO, and SO2 have decreased significantly in the past 10 years, and emissions of all criteria

pollutants have shown improvement (decreased) as

shown in the table below.

Additional information on the SLAMS/NAMS

network is available via the Internet at

http://www.epa.gov/oar/oaqps/qa/monprog.html

Data for each site in the network and the annual

trends report showing national and local air quality

are publicly available via the Internet at

http://www.epa.gov/airsdata/monitor.htm

and http://www.epa.gov/oar/aqtrnd97/

The USEPA administers the SLAMS/NAMS

networks.

Percent decrease in emissions and air concentrations

(1986–1995), U.S. Environmental Protection Agency

National Air Quality Status and Trends Report, 1995

Criteria

pollutant

Percent decrease

in emissions

Percent decrease

in air concentrations

CO 16 37

Lead 32 78

NOx 3 14 (NO2)

Ozone -- 6

PM-10* 17 22

SO2 18 37

*PM-10 measurements began in 1988.

Additional information on PAMS is available

via the Internet

at http://www.epa.gov/oar/oaqps/pams

Figure 4. Photochemical Assessment Monitoring Networ

PAMS

Photochemical Assessment Monitoring Stati

(PAMS) measure ozone precursors (approximately

60 volatile hydrocarbon and carbonyl compounds).

The Clean Air Act requires a PAMS Network in ea

ozone nonattainment area that is designated serious

severe, or extreme. Each nonattainment area has fro

two to five sites, depending on its population. The

current PAMS Network has over 80 sites. The chief

objective of PAMS data collection is to provide an 

quality data base that will assist air-pollution contro

agencies in assessing and, if necessary, refining con

strategies for attaining the National Ambient Air

Quality Standard for ozone. Ambient concentration

ozone and ozone precursors are measured to make

attainment/nonattainment decisions, aid in tracking

VOC and NOx emission inventory reductions, char

terize the nature and extent of the ozone problem, a

identify air-quality trends. In addition, data from

PAMS provide an improved data base for evaluatin

photochemical model performance, especially for

future control strategies as part of the continuing ai

quality management process. The data are particula

useful to States so that the most cost-effective regu

tory controls are implemented. The USEPA provide

funding and oversight for the PAMS networks.
NAD

NADP/NTN

Since 1978, when 18 sites were placed into

operation, the National Atmospheric Deposition

Program/National Trends Network (NADP/NTN) has

grown and evolved. The network now provides a longterm, high-quality data base that is useful for assessing

the magnitude of the acid rain problem and for determining spatial and

temporal trends in

the chemical composition of the atmosphere and the

removal of atmospheric compounds

as deposition. The

NADP/NTN

Network is the only

long-term deposition monitoring

program in the

United States with

national coverage.

Today the

NADP/NTN consists

of over 200 sites and is

cooperatively funded and operated by over 100 organizations, including 8 Federal agencies, State and local

agencies, universities, and private industries. The

combined funding supports program management, site

operation and maintenance, chemical analysis, data

management, and quality assurance. The network has

one of the longest multisite records of precipitation

chemistry in the world and has maintained an effective

quality-assurance program throughout the years.

Recently, an analysis of NADP/NTN d

undertaken to examine the effects in 1995 of 

Title IV of the Clean Air Act Amendments o

The results indicate that Phase I has reduced 

in the Eastern United States. Specifically,

the analysis shows that, in the Northeastern 

States, the dramatic reduction in SO2 emissi

occurred in 1995 resulted in a significant red

the acidity a

concentratio

precipitatio

largest redu

acidity and 

concentratio

tation occur

Ohio River 

region, whe

of the affect

IV sources 

located, as w

sites to the 

where the p

reductions i

sion occurre

sulfate, nitr

sition has sh

considerable variability. Deposition of amm

which along with nitrate is a significant cont

nitrogen enrichment to ecosystems, has been

increasing since the early 1980’s.

As principal NADP/NTN coordinator 

Federal agencies, the U.S. Geological Survey 

a significant portion of the network’s fundin

 ATMOSPHERIC DEPOSITION

The relation between air quality and the environmental impacts air pollutants have on land a

resources is well recognized. The monitoring of wet and dry atmospheric deposition focuses 

on the transfer of chemical substances from the atmosphere to terrestrial and aquatic eco

Atmospheric deposition data furnish important information on chemical flux and are a perf

measure for air-quality researchers and regulatory agencies. The same data provide 

information for environmental studies by ecologists, foresters, hydrologists, and agricultural s

in assessing the influence of atmospheric inputs to the Earth’s surface.

Data and additional information from 

NADP/NTN are available via the Inter

http://nadp.sws.uiuc.edu/ and

http://bqs.usgs.gov/acidrain/

Figure 5. The NADP/NTN.
8 The Role of Monitoring Networks in the Management of the Nation’s Air Quality

Percent change in 1995

nitrate concentration in

precipitation

Percent change in 1995

sulfate concentration in

precipitation

 NADP/MDN

In 1996, the Mercury Deposition Network

(MDN) of NADP was established to develop a

regional data base on the weekly concentrations of

total mercury in precipitation and the seasonal and

annual flux of total mercury in wet deposition. Atmospheric deposition is the prevalent source of mercury

to aquatic ecosystems. The data are used to develop an

information data base on spatial and seasonal trends in

mercury deposited to surface waters, forested watersheds, and other sensitive receptors. Mercury is of

special concern to State and local governments

because 37 States now post health advisories for the

consumption of gamefish with excessive mercury

levels. Most advisories are issued in areas lacking

point sources of mercury. The MDN has grown to be

the largest network in the United States measuring

total mercury in precipitation. More than 35 sites are

currently in operation. The MDN utilizes a specially

designed collector, tested and proven for mercury and

other trace metals.

Around 20 State, Federal, and private organizations support the NADP/MDN. The Minnesota Pollution Control Agency and the Wisconsin Department of

Natural Resources are the two largest participants in

the program.

Figure 7. NADP/MDN.

Data and additional information from the

NADP/MDN are available via the Internet at

http://nadp.sws.uiuc.edu/

Figure 6. Changes in precipitation chemistry, 1995.
CA

CASTNET EPA 

CASTNET NPS 

PS

PA

PE

WS

CTH

SP

KE

MK

DCP

AN

BE LRL

CDR

VP

OXF

LY

UVL

CND

ES PN

AR

BVL

MC

HOW

SAL

PR

AS

CK

COW

ST

BWR VI

BF

WS

LYE

AB

WEL

CAD CVL

SND

GA

SU

ALH

GTH

PND

CNT

SI

CDZ

QAK

LIV

CAT

EGB

BB

SE

JOT

YO

ME

ROM

CAN

MOR

LAV

GRB

DE

VO

PI

NCS

SHN

CHA

EV

GRS

AC

OLY

THR

GLR

GRC

YEL

05/18/99

CASTNET

The Clean Air Status and Trends Network

(CASTNet) was developed to establish an effective

monitoring and assessment network to determine the

status and trends of air-pollution levels, to define their

spatial distribution, to assess their environmental

effects, and to develop a scientific data base for effective evaluation of air-quality management. The

network consists of approximately 80 monitoring

stations across the United States. Unlike

SLAMS/NAMS, most CASTNet sites are located

away from local sources of pollution in order to assess

broad regional air-quality trends. In contrast to the

NADP, which measures wet atmospheric deposition,

CASTNet focuses on dry deposition and, more

recently, has an additional component to address fine

particles and visibility. CASTNet measures ambient

concentrations of gaseous phase pollutants and aerosols along with meteorological parameters needed to

estimate deposition velocities and dry deposition

fluxes of these constituents. Dry deposition fluxes

generally cannot be measured directly; meas

are possible only under highly constrained c

A number of investigations, however, have s

fluxes can be reasonably inferred by couplin

concentration data with meteorological mea

CASTNet is the only broad source of 

sition data in the country. The data are used 

mine relations among emissions, air quality, 

deposition and to provide information neces

understand the ecological effects of atmosph

sition. With over a decade of data collected, 

provides critical information necessary in be

marking and understanding the impact of po

the environment and the effectiveness of pol

management programs.

The USEPA administers the CASTNet 

The National Park Service, in cooperation w

USEPA, operates 19 of these sites.

Figure 8. CASTNet sites.

Data and additional information on CASTN

are available via the Internet at

http://www.epa.gov/acidrain/castnet/

 CASTNet
10 The Role of Monitoring Networks in the Management of the Nation’s Air Quality

C

AIRMoN DRY and WET DEPOSITION MONITORING SITES

Sequoia NP

7/01/86

Lost Dutchman SP

12/10/91

Pawnee Grasslands 

7/01/86 - 2/13/90

Whiteface Mtn.

8/07/84 Borden

6/17/86 - 11/29/88

ANL CORE

11/27/84

Bondville

6/26/85 Howland Forest

6/22/87

West Point

8/04/84

Penn. State

8/09/84 CORE

10/92 Wet

Wye Res. & Ed. Ctr.

12/01/92 Dry

11/95 Wet

Shenandoah NP

11/05/86 - 9/25/90 OR

8/03/84 CORE

10/92 Wet Panola SP

8/27/85

OR Tower

8/19/86

Proctor Maple RC

8/04/92

Huntington Forest

7/28/90

Tampa Bay

8/96

Lewes

10/92

Ithaca

10/92

Oxford

10/92

Smith Island

11/95

Dry Deposition Site

Wet Deposition Site Wet Deposition and CORE Site

Dry and Wet Deposition Site

CORE Site

AIRMON

The Atmospheric Integrated Research Monitoring Network (AIRMoN) is an array of stations

designed to provide an intensive, research-based foundation to support the routine operations of the Nation's

deposition monitoring networks—the National Atmospheric Deposition Program (NADP) for wet deposition, and the Clean

Air Status and

Trends Network

(CASTNet) for dry

deposition. A

subprogram is specifically designed to

detect the benefits of

emissions controls

mandated by the

Clean Air Act

Amendments of 1990

and to quantify these

benefits in terms of

deposition to sensitive areas.

AIRMoN

combines two previously existing deposition research

networks with related

measurement characteristics (previously known as the MAP3S precipitation chemistry network and the CORE/satellite Dry

Deposition Inferential Method network). The

combined sites operate in parallel, with consistent

operational and data aggregation protocols, thus

enabling wet and dry deposition data to be incorporated efficiently into on-line modeling and analysis

applications.

AIRMoN operating principles are designed to

quantify the extent to which changes in emissions

affect air quality and deposition at selected locations.

AIRMoN sites are chosen to optimize the probability

for detecting projected changes and to serve related

measurement needs of researchers studying the effects

of atmospheric deposition. Specific sites are emphasized where operations of different observing arrays

can be collocated. Such Collocated Operational

Research Establishments ("CORE sites") serve two

additional distinct purposes: (a) to provide linkages

among network programs operating to address

different needs with different protocols and (b) to

provide the detailed measurements necessary to und

stand important processes. A strong linkage with the

emerging National

Environmental

Monitoring Framework resulted.

The wet dep

sition component o

the AIRMoN

program

(NADP/AIRMoN)

was initiated in 199

as a network of the

National Atmospheric Deposition

Program.

NADP/AIRMoN

provides precipitation chemistry data

with a greater

temporal resolution

than what is available from the

NADP/NTN. In 1999, the NADP/AIRMoN compris

10 monitoring stations where precipitation samples a

collected every 24 hours. The daily samples are

analyzed for the same constituents as the NADP/NT

weekly network. Daily monitoring data are used to

provide additional resolution to evaluate the effectiv

ness of air-quality regulations and emission trading

practices. One of the primary applications of the dai

data is identifying the source areas of atmospheric

pollution via back-trajectory analyses. Also possible 

the calibration of models, which are used in estimatin

changes in atmospheric deposition, as a result of

changing emissions.

The AIRMoN program is coordinated and

funded primarily through the National Oceanic and

Atmospheric Administration (NOAA).

Figure 9. AIRMoN.

Additional information and data for AIRMoN

are available via the Internet at

http://www.arl.noaa.gov/research/programs/airmon.html

and http://nadp.sws.uiuc.edu/

AIRMoN
GASEOUS POLLUTANT MONITORING PROGRAM (G

GASEOUS POLLUTANT MONITORING

PROGRAM (GPMP)

To meet its general responsibilities with respect

to air resource management, the National Park Service

(NPS) has established a framework to protect,

preserve, and enhance the air quality in units of the

National Park system, particularly Class I areas. This

framework is heavily dependent on comprehensive

monitoring programs to determine the levels of

gaseous pollutants, fine particles, and visual air quality

occurring or affecting National Parks. The gaseous

pollutant monitoring

program (GPMP) has

historically concentrated on

determining the levels of

two air pollutants—

ozone and sulfur dioxide.

These pollutants are particularly toxic to native vegetative species found in

National Park Service units

at levels at or below the

National Ambient Air

Quality Standards established by the USEPA for

these two pollutants.

The primary monitoring objectives for the gaseous

pollutant-monitoring program

are to:

• Establish existing or baseline concentrations and

assess trends in air quality in NPS units.

• Determine compliance with national air-quality

standards.

• Assist in the development and revision of national

and regional air-pollution control policies

affecting park resources.

• Provide data for atmospheric model development

and evaluation.

• Identify those air pollutants with the potential to

injure or damage park natural resources, monitor

these pollutants, and correlate observed effects

on these resources to ambient levels of these

pollutants.

All gaseous pollutant monitoring stations are

equipped with continuous ozone monitors, with some

also containing continuous sulfur dioxide monitors.

Most stations also are equipped with meteor

towers for the measurement of wind speed a

tion, temperature, dew point or relative humi

radiation, and precipitation.

Currently, ozone monitoring is being c

either by the NPS or State agencies in 26 of 

48 Class I areas. In addition, the NPS and St

monitor ozone and other pollutants in seven 

areas designated as “Class II.” Intensive, or e

monitoring of ozone and its precursors is cu

being conducted in three eastern parks—Gre

Mountains, Mamm

Cave, and Shenan

a means of unders

the atmospheric a

ical processes cau

levels of ozone m

these parks and th

reduce these level

of the enhanced m

effort is a result o

tive efforts with o

cies, universities, 

industry. A new c

of the program is 

experimentation i

of low-cost, passi

samplers to measure o

sulfur dioxide, and nitr

oxides as a way of sup

menting the continuous monitoring program

devices can be used to investigate the existen

spatial extent of air- pollution problems in p

The NPS gaseous pollutant program i

leveraged program. Through effective partne

with the USEPA, other Federal and State age

industry, the NPS has been able to maintain 

gaseous pollutant monitoring program for ov

10 years. The NPS commitment to long-term 

toring of air pollutants in National Parks has 

others to use parks as outdoor laboratories fo

advancement of science and their own resear

ests. This synergism allows NPS managers t

more informed air-resource management dec

The USEPA’s decision to use 12 National Pa

backbone of a national UV-B monitoring ne

was heavily influenced by the availability of 

quality data in these parks. Thus, NPS data c

ment other scientific and research efforts in 

country.

Figure 10. Gaseous Pollutant Monitoring

Program (GPMP).
12 The Role of Monitoring Networks in the Management of the Nation’s Air Quality

HOW IMPORTANT IS THE CURRENT

MONITORING INFRASTRUCTURE IN

ADDRESSING EMERGING ISSUES?

The existing network of air-quality monitoring

sites provides a low-cost infrastructure that is readily

modified to include new atmospheric chemical species

of interest. The ability of emerging monitoring

programs to build on an established traditional infrastructure (e.g., trained site operators, secured and welldocumented sites, and field laboratories) has resulted

in lower start-up costs and quicker implementation

schedules for new measurement objectives. Also

important for new initiatives is the ability to access the

substantial knowledge-based infrastructure associated

with a monitoring network, such as trained datamanagement and quality-assurance specialists, sophisticated data- and site-management tools, and data

dissemination (e.g., interactive Internet-based servers

for supplying air-quality data to a worldwide user

base).

One example of this synergy between new and

existing air-quality monitoring activities was the

recent initiation of a monitoring program to measure

atmospheric deposition of mercury in the United

States and Canada. In this effort, the existing infrastructure of the long-established NADP/NTN facilitated a quick and successful start-up for the new

NADP Mercury Deposition Network (NADP/MDN).

Although Federal agencies support only a few of the

currently operated MDN sites, support via the specialized personnel, computer facilities, and network

management tools enabled the MDN to come on line

as a nearly 40-site operation in 3 years.

The importance of collocating air-quality monitoring equipment at key sites throughout the United

States is increasingly recognized as critical to understanding the relation between atmospheric air-quality

data and deposition-flux measurements. Recently, the

National Park Service and the USEPA have designated

14 park monitoring locations as Prime Net (Park

Research and Intensive Monitoring of Ecosystems

Network) sites. The 14 sites have monitors for

IMPROVE, CASTNet, NADP/NTN, ozone, and

UV-B. Sites at Penn State University and Bondville,

Illinois, have monitors from NADP/NTN,

NADP/AIRMoN, AIRMoN Dry, and CASTNET.

In 1997, the USEPA issued final revisions to

strengthen the particulate-matter standards by adding

new standards that provide more stringent goals for

fine particles in air (PM-2.5). The USEPA issued fin

revisions to the primary (health-based) PM standard

by adding a new annual and 24-hour standard. The

deployment of a new monitoring network is a critica

component of the PM-2.5 standard. New instrument

tion is being deployed, taking advantage of the

existing network infrastructure (i.e., IMPROVE and

NAMS/SLAMS), coordinating and integrating the

existing visibility-monitoring requirements with the

new ambient air-quality monitoring programs. The

expanded network will include compliance monitors

continuous monitors, special purpose monitors, chem

ical speciation sampling and analysis sites, and speci

study sites to optimize the results for priority researc

THE ROLE OF THE COMMITTEE ON THE

ENVIRONMENT AND NATURAL

RESOURCES (CENR), AIR QUALITY

RESEARCH SUBCOMMITTEE (AQRS)

Over the past 25 years, support for the type of

monitoring networks described in this document has

been sporadic. Support shifts with the political atten

tion given to a particular environmental issue.

Commonly, a phenomenon is asserted to be a major

environmental problem and the lack of information

that would be needed to understand its nature, exten

and impact is decried. A program of monitoring and

research is instituted to gather the knowledge needed

to develop an appropriate policy response. A respon

is fashioned and implemented, and frequently a pledg

is given to continue environmental monitoring to eva

uate the effectiveness of the policy actions. However

the monitoring program associated with the issue

enters an almost immediate decline as new issues ar

identified, and limited resources are demanded by

other problems. In this phase, budget-driven change

such as temporary shutdowns, site moves or closure

changes in sampling intervals, and reductions in

quality assurance and quality control diminish the

value of the long-term data set due to overall loss of

continuity in the historical record. The inefficiency o

this approach imposes additional direct and hidden

costs on the Nation’s financial resources. The start-u

and shutdown costs of designing and implementing

networks are significant. A lack of coordination

between existing and new monitoring efforts adds to

the delays in addressing emerging issues and to the

cost of generating the information required to develo
THE ROLE OF THE COMMITTEE ON THE ENVIRONMENT AND NATURAL RESOURCES (CE

AIR QUALITY RESEARCH SUBCOMMITTEE (AQ

sound policy. Finally, the value of an extensive timeseries record extends beyond the identification of a

specific problem. Long-term time series permits verification that decisions are effective; solutions are,

indeed, working; and the ongoing costs and benefits of

the given control program are assessed accurately.

The AQRS has identified the air-quality monitoring networks deemed critical for baseline airquality data in the United States and initiated action to

promote research and development on approaches to

ensure that existing networks are adaptable to change.

Agencies that fund existing core networks are encouraged to consider enhancing the capabilities of these

networks through adding constituents and other capabilities in response to emerging issues rather 

terminating support for one network in order 

support another. Agencies will be encourage

dinate quality-assurance efforts, network int

isons, and sampling equipment collocations. 

stop shopping approach for air-quality monit

via the Internet will be promoted. By increas

accessibility for the academic and research c

ties, the investment in these networks can be 

by increasing the number of research applica

interpretive studies. Finally the CENR, AQR

encourage increased involvement and review 

existing monitoring programs by the researc

nity and help design more efficient and less 

ones as needed in the future.
For additional information, please contact:

Environment Division

Office of Science and Technology Policy

Executive Office of the President

Washington, DC 20502

Telephone: 202-456-6202

Fax: 202-456-6025

Also available on the NSTC Home Page via link from the OSTP Home Page at:

http://www.whitehouse.gov/WH/EOP/OSTP/NSTC/html/nstc_pubs.html
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