2010 Annual Monitoring Network Plan 

Prepared by the Air Monitoring Section of Antelope Valley Air Quality Management 

District to meet the requirements of 40 CFR PART 58, SUBPART B. 

Eldon Heaston, Executive Officer 

Bret Banks , Manager 

Christopher A. Collins, Supervisor 

Aleksey Astakhov, Air Quality Instrument Technician 

Fred Wohosky, Air Quality Instrument Technician 

Orlando Salinas, Associated Air Quality Specialist 

Antelope Valley Air Quality Management District, 43301 Division Street, Suite 206, Lancaster CA. 

93535
2

Table of Contents 

40 CFR PART 58, SUBPART B 

REQUIREMENTS...........................................................................................................................3 

ABOUT THE ANTELOPE VALLEY AIR QUALITY MANAGEMENT DISTRICT ................4 

NETWORK DESIGN ...............................................................................................................................5

OVERVIEW OF MDAQMD MONITORING STATIONS .............................................................5 

CRITERIA POLLUTANT STANDARDS ..................................................................................6 

INDIVIDUAL SITE DATA: 

LANCASTER ........................................................................................................................................7 

EPA OZONE MAPPING 

....................................................................................................................................................................9 

APPENDIX: 

DEFINITION OF 

TERMS.................................................................................................................................................10 

CRITERIA POLLUTANT INFORMATION....................................................................................12 

NATIONAL AMBIENT AIR QUALITY STANDARD...................................................................14 
3

40 CFR Part 58, Subpart B Requirement 

This 2010 Annual Air Monitoring Network Review is being submitted by the Antelope Valley Air 

Quality Management District’s Air Monitoring Section to the United States Environmental Protection 

Agency (US EPA) Region 9. The network review evaluates the adequacy of the ambient air monitoring 

network with respect to the monitoring objectives and spatial scales. This annual assessment is required 

by 40 CFR Part 58, Subpart B. This Network Review is also preliminary to the annual data certification

with the US EPA and helps Air Districts assess the quality of their data before submitting for data 

certification. This network review has the secondary purpose of informing the public of the criteria air 

pollutants that can affect their health, how the Mojave Desert AQMD monitors these criteria pollutants, 

and what the actual readings are so that our citizens can make informed decisions regarding their 

lifestyles. 
4

About the Antelope Valley Air Quality Management District 

The AVAQMD comprises over 1,300 square miles. From the Kern County line on the north, the San 

Gabriel and Tehachapi Mountains to the south and west and the San Bernardino County line to the east 

nearly 400,000 inhabitants depend on air quality regulation for healthful, cleaner air. 

For decades the Antelope Valley air quality was managed by a regional air quality organization that was 

100 miles away and of a totally different mind set. The dream of local business people was realized when 

state legislation created the Antelope Valley Air Pollution Control District, on July 1, 1997. On January 

1, 2002, the AV Air Pollution Control District broke away from the County of Los Angeles and became 

the AV Air Quality Management District, an independent agency. Today, AVAQMD is responsible for 

regulating stationary sources of air pollution located within its 1,300 square mile jurisdiction. 

For the first time, there were local officials and local staff to which Antelope Valley citizens and 

businesses could turn for assistance. Consisting of representatives from local cities, Los Angeles County 

and the public at large, the District worked hard to simplify rules and eliminate regulations that simply did 

not apply to the desert air shed quality issues. 
5

NETWORK DESIGN 

Purpose and Objective of the Network 

The purpose of the ambient air monitoring network is to assess the extent of air pollution, ensure 

compliance with national legislation, evaluate control options, and provide data for air quality modeling. 

In general, six basic monitoring objectives and five measuring scales are used to determine the network 

design (see Table 2 and Table 3). Additional considerations such as availability of power, accessibility to 

site, security, geographic location, and fiscal and personnel resources are also addressed in determining 

the feasibility of the network design. 

Table 2 Site Monitoring Objectives 

1. Determine highest concentrations expected to occur in the area covered by the network.

2. Determine representative concentrations in areas of high population density.

3. Determine the impact on ambient pollution levels of significant sources or source categories.

4. Determine general background concentration levels.

5. Determine the extent of regional pollutant transport from populated areas, with regards to the 

secondary standards (such as visibility impairment and effects on vegetation).

6. Determine the welfare-related impacts in more rural and remote areas.

To establish or evaluate a site, one must link its monitoring objectives to the physical location of the site. 

This can be done by matching the spatial scale, which represents the sample of air around the monitor 

where pollutant concentrations are reasonably uniform, with the most appropriate monitoring objective.

Thus, spatial scale represents the physical dimensions of the air parcel around the monitor, and 

monitoring objective represents the overall purpose of the monitor. Combining the proper spatial scale

with the monitoring objective explains why air monitoring sites are located in particular areas. 

Table 3 Spatial Measurement Scales 

Scale Defined parameter (radius) 

Micro Scale 0 to 100 meters

Middle Scale 100 to 500 meters

Neighborhood Scale 0.5 to 4 kilometers

Urban Scale 4 to 50 kilometers

Regional Scale 10 to 100s of kilometers

Since it is physically and fiscally impossible to monitor air quality in every location, representative 

samples must be obtained. The optimal locations for obtaining these samples are determined by using the 

monitoring objectives and the spatial measurement scales described above. For example, there might be 

numerous locations where the highest concentration of particulate matter may occur. Using these 

principles, only one or two sites will be established to represent all of the high-concentration areas. The 

same reasoning can be used for different 

types of pollutants. This does not mean that the number of monitoring sites is fixed. To the contrary, the 

network must be dynamic enough to maintain a current representative sample of the air quality. 

Overview of the AVAQMD Monitoring Station

AVAQMD currently operates a network of 1 monitoring site. The following is a brief description of that 

site: 

Lancaster this site is located at 43301 Division Street, Lancaster, CA. 

This represents the most densely populated area in the Antelope Valley Desert Air Basin.
6

Criteria Pollutant Standards 

Carbon Monoxide (CO) 

There are two primary standards for CO, the 8-hour average and the 1-hour average. The 8-hour primary 

standard is 9 ppm and the 1-hour primary standard is 35 ppm. A violation of the standard is any two 

exceedances in a calendar year. 

Ozone (O3) 

The 1-hour average ozone standard was revoked by the EPA on June 15, 2005, and has been replaced by 

the 8-hour average standard for compliance purposes. 

The eight-hour primary standard for ozone is 0.075 ppm. Compliance with the standard is determined by 

averaging the 4th highest eight-hour average over a three-year period. This three-year average must be

less than or equal to 0.075 ppm 

Particulate Matter <=10 Microns (PM10) 

The 24-hour Primary standard for PM10 is 150 μg/m3 (155 μg/m3 with mathematical rounding). This 

standard is violated when the expected number of exceedance for the calendar year is more than one. A 

formula, as detailed in 40 CFR 50, is used to determine the expected number of exceedances. The formula 

takes into account the number of days sampling occurred and the number of valid samples collected. A 3-

year average of these estimated days is then used to determine compliance. On December 18, 2006 new 

monitoring rules from the EPA revoked 

the PM10 annual primary standard

Particulate Matter <=2.5 Microns (PM2.5) 

On December 18, 2006, the EPA implemented new primary standards for PM2.5. These new rules 

changed the 24-hour average standard from 65 μg/m3 to 35 μg/m3. The annual average standard of 15 

μg/m3 remains unchanged. 

Compliance with the 24-hour standard is determined by taking the 3-year average of the 98th percentile at 

each monitoring site. Compliance with the Annual standard is determined by taking the 3-year average of 

the spatially averaged annual means. 

Nitrogen Dioxide (NO2) 

Compliance with the NO2 standard is achieved when the annual arithmetic mean concentration in a 

calendar year is less than or equal to 0.053 ppm, rounded to three decimal places. 

Sulfur Dioxide (SO2) 

A violation of the primary standard occurs when the annual mean exceeds 0.030 ppm or when a 24-hour 

average of 0.14 ppm is exceeded more than once per calendar year. A violation of the 3-hour average 

secondary standard occurs when a 3-hour average of 0.5 ppm is exceeded more than once per year 
7

AQS ID 060379033 

GIS COORDINATES N34deg. 40’10”, W118deg. 7’50” 

LOCATION AVAQMD Building 

ADDRESS 43301 Division St. 

COUNTY Los Angeles County 

DISTANCE TO ROAD 25 Meters 

TRAFFIC COUNT 30000 

GROUND COVER Roof 

FLOW AUDIT 4/2/2009 

REPRESENTATIVE AREA Desert portion of Los Angeles County

Pollutant 03 N02 S02 C0 PM10 PM2.5 TEOM WDR 

Monitor Objective Transport Population Population Population N/A N/A N/A N/A 

Monitor Purpose SLAMS SLAMS SLAMS SLAMS SLAMS SLAMS SLAMS SLAMS 

Spatial Scale NBHD NBHD NBHD NBHD NBHD NBHD NBHD NBHD 

Sampling Method API 400 API 200A API 100A API 300A ANDR R&P 2000 R&P 

1400A 

CLIMA 

Analysis Method UV ABS CHEM FLUOR GFC MDLAB MDLAB MICRO AERO 

Start Date May - 01 May - 01 May - 01 May - 01 May - 01 May - 01 May - 01 May - 01 

Operation Schedule CONTIN CONTIN CONTIN CONTIN 1:6 1:6 CONTIN CONTIN 

Sampling Season All Year All Year All Year All Year All Year All Year All Year All Year 

Probe Height (meters) 9.4 9.4 6.9 9.4 9.0 9.0 9.0 13.6 

Distance from 

supporting structure 

N/A N/A N/A N/A N/A N/A N/A N/A 

Distance from 

obstruction on roof 

N/A N/A N/A N/A N/A N/A N/A N/A 

Distance from structures 

not on roof 

N/A N/A N/A N/A N/A N/A N/A N/A 

Distance from trees N/A N/A N/A N/A N/A N/A N/A N/A 

Distance between 

collocated monitors 

N/A N/A N/A N/A N/A 2 meters N/A N/A 

Unrestricted airflow 

(deg) 

360 deg 360 deg 360 deg 360 deg 360 deg 360 deg 360 deg 360 deg 

Probe Material TEFLON TEFLON TEFLON TEFLON TEFLON TEFLON TEFLON TEFLON 

Residence Time (sec) 14.2 15.4 16.3 13.8 N/A N/A N/A N/A 

Changes within the next 

18 months 

NO NO NO NO NO NO NO NO 

Suitable for comparison 

to the annual PM2.5? 

N/A N/A N/A N/A N/A YES N/A N/A 

*CHEM Chemluminescence *FLUOR Fluorescence 

*GFC Gas filter Correlation *MDLAB MDAQMD LAB 

 *NBHD Neighborhood *MICRO Microbalance 

*ANDR Andersen *CLIMA Climatronics 

*AERO Aero vane *PYRAN Pyranometer 

*THERM Thermistor *CONTIN Continuous 

*PIEZO Piezoresistive 

*UV ABS UV ABSORPTION 

*ANEMO Anemometer 

5 YEAR TREND OXONE EXCEEDANCES

 

 STATE 

1HR. 

STATE 

8HR. 

FED 

1HR 

FED 

8HR. 

2005 22 2 16 

2006 16 0 14 

2007 18 59 0 39 

2008 22 70 0 46 

2010 

NUMBER OF OCCURANCES 
8

AQS ID 060379033 

GIS COORDINATES N34deg. 40’10”, W118deg. 7’50” 

LOCATION AVAQMD Building 

ADDRESS 43301 Division St. 

COUNTY Los Angeles County 

DISTANCE TO ROAD 25 Meters 

TRAFFIC COUNT 30000 

GROUND COVER Roof 

FLOW AUDIT 4/2/2009 

REPRESENTATIVE AREA Desert portion of Los Angeles County

Pollutant WSP TMP PRESS 

Monitor Objective N/A N/A N/A 

Monitor Purpose SLAMS SLAMS SLAMS 

Spatial Scale N/A N/A N/A 

Sampling Method CLIMA CLIMA CLIMA 

Analysis Method ANEMO THERM PIEZO 

Start Date May - 01 May - 01 May - 01 

Operation Schedule CONTIN CONTIN CONTIN 

Sampling Season All Year All Year All Year 

Probe Height (meters) 13.6 15.9 1.5 

Distance from 

supporting structure 

N/A N/A N/A 

Distance from 

obstruction on roof 

N/A N/A N/A 

Distance from structures 

not on roof 

N/A N/A N/A 

Distance from trees N/A N/A N/A 

Distance between 

collocated monitors 

N/A N/A N/A 

Unrestricted airflow 

(deg) 

360 deg 360 deg 360 deg 

Probe Material TEFLON TEFLON TEFLON 

Residence Time (sec) N/A N/A N/A 

Changes within the next 

18 months 

NO NO NO 

Suitable for comparison 

to the annual PM2.5? 

N/A N/A N/A 

*CHEM Chemluminescence *FLUOR Fluorescence 

*GFC Gas filter Correlation *MDLAB MDAQMD LAB 

 *NBHD Neighborhood *MICRO Microbalance 

*ANDR Andersen *CLIMA Climatronics 

*AERO Aerovane *PYRAN Pyranometer 

*THERM Thermistor *CONTIN Continuous 

*PIEZO Piezoresistive 

*UV ABS UV ABSORPTION 

*ANEMO Anemometer 
9

Figure 1: Looking at station from the NorthWest 

Figure 2: Looking at proves from the North. 

Figure 3: Looking at probes from the East. 

PM10 Sampler 

PM2.5 Sampler 

Gas sample probe 

TEOM sample probe. 
10

EPA Ozone Mapping 

The AIRNOW website (http://www.epa.gov/airnow) provides real-time air pollution (ozone and PM2.5) 

maps for major metropolitan areas around the United States, including the Mojave Desert Air Quality 

Management District. The MDAQMD has participated in the program since 2001. 

This website can be used as a tool for which the public can plan their daily activities and limit their 

exposure to air pollution. Eight-hour average peak ozone concentration maps and real-time eight-hour 

ozone animation maps are provided. Colors on the map indicate different concentrations of ozone 

pollution. The one-hour average values are given in parts per billion. The eight-hour averages are 

converted into Air Quality Index (AQI) numbers. The AQI is based on the NAAQS. The index was 

developed to convert pollution measurements into a common index that the general public can more 

easily understand. 

Air Quality Index 

Levels of Health Concern

Numerical

Value Meaning

Good (GREEN) 0-50 Air quality is considered satisfactory, and air pollution poses little 

or no risk. 

Moderate (YELLOW) 51-100 

Air quality is acceptable; however, for some pollutants there may 

be a moderate health concern for a very small number of people 

who are unusually sensitive to air pollution. 

Unhealthy for 

Sensitive Groups (ORANGE) 101-150 Members of sensitive groups may experience health effects. The general public is not likely to be affected. 

Unhealthy (RED) 151-200 Everyone may begin to experience health effects; members of 

sensitive groups may experience more serious health effects. 

Very Unhealthy (PURPLE) 201-300 Health alert: everyone may experience more serious health 

effects. 

Hazardous (MAROON) > 300 Health warnings of emergency conditions. The entire population 

is more likely to be affected.
11

DEFINITION OF TERMS

AQS: Environmental Protection Agency’s Air Quality System 

Attainment: This refers to the NAAQS used to comply with the federal Clean Air Act. After several 

years of no violations of the NAAQS, the EPA can classify the area as in attainment for that pollutant. 

CFR: Code of Federal Regulations. 

Class I: Federally designated park or wilderness area with mandated visibility protection. 

CO: Carbon monoxide. 

Criteria Pollutants: Six pollutants (CO, Lead, NO2, O3, Particulates, and SO2) that have NAAQS 

established by the US EPA. 

Delta T: Difference between two levels of temperature measurements. 

Design Value: A design value is a statistic that describes the air quality status of a given area relative to 

the level of the NAAQS. For a concentration-based standard, the air quality design value is simply the

standard-related test statistic. The design value of a pollutant monitoring network is the highest sample 

value in the network used to compare to the NAAQS; e.g. the 24-hour PM2.5 design value for the 

network is the monitor with the highest 3-year average of the 98th percentile. 

EPA: U. S. Environmental Protection Agency. 

Exceptional Events: An uncontrollable event caused by natural sources of pollution or an event that is 

not expected to recur at a given location. 

HAPs: Hazardous air pollutants. An air-born chemical that has been listed in the federal Clean Air Act 

and has an associated standard or process requirement determined for it. 

AVAPCD: Antelope Valley Air Quality Management District 

μg/m3: Microgram per cubic meter. 

MSA: Metropolitan Statistical Area. A geographical area designated by the federal government based on 

the concept of a core area with a large population nucleus, plus adjacent communities having a high 

degree of economic and social integration with that core. 

NAAQS: National Ambient Air Quality Standards. A health and welfare-based standard that is set by the 

US EPA to qualify allowable levels of criteria pollutants. 

NO2: Nitrogen dioxide. 

NOX: Sum of nitrogen oxide and NO2. 

O3: Ozone. 

Pb: Lead. 
12

PM: Particulate matter. Material suspended in the air in the form of minute solid particles or liquid 

droplets. 

PM2.5: Particulate matter of 2.5 Microns in diameter or smaller 

PM10: Particulate matter of 10 Microns in diameter or smaller. 

PPM: Parts per million. 

Primary Standard: One portion of the NAAQS. These standards are designed to protect the public 

health. 

Secondary Standard: The less stringent portion of the NAAQS designed to protect property and the 

environment. 

SIP: State Implementation Plan. SIPs are a collection of state and local regulations and plans to 

achieve healthy air quality under the Clean Air Act. 

SLAMS: State and Local Air Monitoring Station. The SLAMS consist of a network of approximately 

5,000 monitoring stations nationwide whose size and distribution is largely determined by the needs of

State and local air pollution control agencies to meet their respective State implementation plan (SIP) 

requirements. Other types of monitoring stations include NCORE (national core) and SPM (special 

purpose) monitors 

SO2: Sulfur dioxide. 

SPM: Special purpose monitor. Special Purpose Monitoring Stations provide for special studies 

needed by the State and local agencies to support State implementation plans and other air 

program activities. The SPMs are not permanently established and can be adjusted easily to 

accommodate changing needs and priorities. 

SSI: Size Selective Inlet. SSI High Volume Samplers are filter-based instruments to measure PM10. 

TEOM: Tapered Element Oscillating Microbalance. A continuous particulate measuring instrument used 

to measure PM10. 

VOC: Volatile organic compounds. VOCs are chemical compounds that can easily vaporize and enter the 

atmosphere. There are many natural and artificial sources of VOCs; solvents and gasoline make up some 

of the largest artificial sources. VOCs will react with NOx in the presence of sunlight to create groundlevel ozone pollution. 
13

CRITERIA POLLUTANT INFORMATION 

Abstract of Pollutants: Certain air pollutants, called “criteria air pollutants,” are common throughout the 

United States. These pollutants can cause health problems, pollute the environment, and cause property

damage. These criteria pollutants are so named since the US EPA has regulations, called the National 

Ambient Air Quality Standards (NAAQS), on 

allowable levels of these substances using health-based criteria. One set of limits, called “primary 

standards”, protect health, while another set of “secondary” standards, is designed to protect property and 

the environment. 

The US EPA names the following pollutants as criteria pollutants: carbon monoxide (CO), lead (Pb), 

nitrogen dioxide (NO2), ozone (O3), particulates (PM10 & PM2.5), and sulfur dioxide (SO2). MDAQMD 

operates monitors for the following criteria pollutants: carbon monoxide, ozone, particulates, nitrogen 

dioxide, and sulfur dioxide. 

MDAQMD does not monitor for lead (Pb) 

Causes and Characteristics of Pollutants 

Carbon Monoxide: 

CO is the most widely distributed and most commonly occurring air pollutant. Total emissions of CO to 

the atmosphere exceed all other pollutants combined, on a weight basis. Fortunately, CO does not persist 

in the atmosphere, but is quickly converted to carbon dioxide (CO2). CO can reach dangerous levels in 

localized areas or hotspots such as heavily traveled intersections or city streets. In addition, CO has been 

implicated in ozone formation. Most people are familiar with CO and are aware that automobiles produce

this deadly odorless and colorless gas. In fact, this gas is produced almost anytime something is burned. 

All substances that are living 

(plants, animals) or that were once living (wood, coal, oil, gasoline) are composed of carbon compounds. 

If these substances are burned in the presence of sufficient oxygen, the carbon is converted to CO2 gas. If, 

as is often the case, not enough oxygen is present, carbon monoxide gas is produced. Carbon monoxide’s 

danger lies in the extremely strong affinity that hemoglobin has for it. Hemoglobin, the special oxygentransporting material in the red blood cell, has approximately 200 times stronger affinity for CO than for 

oxygen. Therefore, if both CO and O2 are present the bonding between the CO and hemoglobin will 

prevent the O2 from exchanging within a person’s body. This puts a heavy burden on people with heart 

disease and can aggravate angina, but even healthy people can suffer from harmful side effects from CO. 

Nitrogen Dioxide: 

NO2 belongs to a family of highly reactive gases called nitrogen oxides. These gases are formed when 

fuel is burned at high temperatures, and are emitted primarily from automobile exhaust and power plants. 

Exposure to nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections, 

particularly in people with existing respiratory illness such as asthma. 

Ozone: 

O3 is a naturally occurring compound in which three oxygen atoms combine together. This is an unstable 

combination, and ozone is continually going through a natural cycle of being formed and then converting 

back to the more stable “normal” double oxygen compound (O2). The cycle occurs fairly rapidly. In the 

stratosphere (6 miles and more above the earth), naturally occurring ozone has a beneficial effect of 

screening out harmful ultraviolet light from the sun. However, ground-level ozone is a pollutant and is a 

component of the regional smog that affects the basin. Ozone is not directly emitted into the air, but rather 

forms in a complex reaction that involves heat, sunlight, and a “soup” of toxic pollutants, especially

volatile organic compounds (VOCs). 
14

Some of the most common sources of VOCs are gasoline vapors, chemical solvents, and combustion 

products of fuels and consumer products. Ozone is created by sunlight acting on nitrates (NOX) and 

VOCs from motor vehicles and stationary sources, and can be carried hundreds of miles from their 

origins. Ozone affects the respiratory system in people and animals, and also affects the growth of plants. 

Particulate Matter: 

Particulate matter is the term for solid or liquid particles found in the air. Particle pollution is made up of 

a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and 

soil or dust particles. While some particles are large or dark enough to be seen as soot or smoke, others 

can only be seen through an electron microscope. In 1987 the EPA replaced the Total Suspended 

Particulates (TSP) air quality standard with a standard for PM10 (particles measuring ten microns or less). 

Health research studies have found that PM10 has the ability to reach the lower regions of the respiratory 

tract, and thus can affect the respiratory system in both humans and animals. Particulates that have high 

acid levels can cause damage to 

man-made materials and reduce visibility. The size of particles is directly linked to their potential for 

causing health problems. EPA is concerned about particles that are 10 micrometers in diameter or smaller 

because those are the particles that generally pass through the throat and nose and enter the lungs. Once 

inhaled, these particles can affect the heart and lungs and cause serious health effects. EPA groups particle 

pollution into two categories: 

• "Coarse particles," such as those found near roadways and dusty industries, range in size from 2.5 to 10 

microns in diameter. 

• "Fine particles," such as those found in smoke and haze, have diameters smaller than 2.5 microns. These 

particles can be directly emitted from sources such as forest fires, or they can form when gases emitted 

from power plants, industries and automobiles react in the air. 

Sulfur Dioxide: 

SO2 is emitted (in gaseous form) largely from burning high-sulfur coal, oil, and diesel fuel. Because this 

gas is usually found in association with particulate pollution, as SO2 is the precursor for fine sulfate 

particles, separating the health effects of these two pollutants is difficult. Together SO2 and PM2.5 make 

up a major portion of the pollutant load in many cities, acting separately and in concert to threaten public 

health. SO2 contributes to respiratory illness, particularly in children and the elderly, and aggravates 

existing heart and lung diseases. SO2 contributes to the formation of acid rain, and it contributes to the 

formation of atmospheric particles that cause visibility impairment, most noticeably in national parks. 

SO2 and the pollutants formed from SO2, such as sulfate particles, can be transported over long distances 

and deposited far from the point of origin. This means that problems with SO2 are not confined to areas 

where it is emitted. 

National Ambient Air Quality Standards 

The EPA Office of Air Quality Planning and Standards (OAQPS) manages programs to improve air 

quality in areas where the current quality is unacceptable and to prevent deterioration in areas where the 

air is relatively free of contamination. To accomplish this task, OAQPS establishes the National Ambient 

Air Quality Standard (NAAQS) for each of the criteria pollutants (see Table 1). 

There are two types of standards. Primary standards protect against adverse health effects; secondary 

standards protect against welfare effects, such as damage to farm crops and vegetation and/or damage to 

buildings. Because different pollutants have different effects, the NAAQS are also different. Some 

pollutants have standards for both long-term and short-term averaging times. The short-term standards are 

designed to protect against acute, or short-term, health effects, while the long-term standards are 

established to protect against chronic health effects. Table 1 lists the NAAQS for six criteria pollutants. 
15

` Table 1 National Ambient Air Quality Standards

The NAAQS set air pollutant concentration limits for six pollutants, called the criteria air pollutants, 

namely carbon monoxide (CO2), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), lead (Pb), 

Particulate Matter (PM10)

[8] and Particulate Matter (PM2.5).[8]

 

The NAAQS for the six criteria pollutants are listed in the table below: 

National Ambient Air Quality Standards [3][4] 

Primary Standard Secondary Standard 

Criteria 

Pollutant 

Concentration 

Limit 

Averaging 

Time 

Concentration 

Limit 

Averaging 

Time 

9 ppmv

( 10 mg/m

3

 ) 8-hour (1)

Carbon monoxide 

35 ppmv 

( 40 mg/m3 ) 1-hour (1)

 

None 

0.03 ppmv 

( 80 μg/m3 ) 

Annual 

(arithmetic mean) 

Sulfur dioxide 

0.14 ppmv 

( 365 μg/m3 24-hour (1)

 

0.5 ppmv 

( 1300 μg/m3 ) 3-hour (1)

 

Nitrogen dioxide 0.053 ppmv 

( 100 μg/m3 ) 

Annual 

(arithmetic mean) Same as primary 

0.075 ppmv 

( 150 μg/m3 ) 8-hour (2) Same as primary 

Ozone 

0.12 ppmv 

( 235 μg/m3 ) 1-hour (3) Same as primary 

0.15 μg/m3 

Rolling 3-month 

average 

Same as primary 

Lead 

1.5 μg/m3 Quarterly average Same as primary 

Particulate 

Matter (PM10) 150 μg/m3

24-hour (4) Same as primary 

15 μg/m3 

Annual (5)

(arithmetic mean) Particulate Same as primary 

Matter (PM2.5) 

35 μg/m3 24-hour (6) Same as primary 

(1) Not to be exceeded more than once per year. 

(2) The 3-year average of the fourth-highest daily maximum 8-hour average at each monitor within the 

area over each year must not exceed 0.075 ppmv. 
16

(3a) The expected number of days per calendar year with maximum hourly averages above 

0.12 ppm must be equal to or less than 1. 

(3b) As of June 15, 2007, the U.S. EPA revoked the 1-hour ozone standard in all areas except 

for certain parts of 10 states. 

(4) Not to be exceeded more than once per year on average over 3 years. 

(5) The 3-year average of the weighted annual mean PM2.5 concentrations from single or multiple 

community-oriented monitors must not exceed 15 μg/m3. 

(6) The 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented 

monitor within the area must not exceed 35.5 μg/m3. 

The units of measure used for concentrations in the above table are parts per million by volume (ppmv), 

milligrams per cubic meter of air at 101.325 kPa and 25 °C (mg/m3), and micrograms per cubic meter of 

air at 101.325 kPa and 25 °C (μg/m 3). See Air pollutant concentrations for the conversions between gas

concentrations ppmv and mg/m3

.