National Ambient Air Quality Standards, NAAQS
The National Ambient Air Quality Standards, as published by The EPA Office of Air Quality Planning and Standards (OAQPS), sets standards for pollutants considered harmful to public health and the environment.
The Clean Air Act (1990) established two types of national air quality standards. Primary standards set limits to protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings.
The NAAQS are used by designers and engineers as a determination of the quality of the outside air that may be brought into a building to clean the inside air by diluting contaminants.If the outside air does not meet the criteria for clean air as defined by the United States Environmental Protection Agency the incoming air should be cleaned before introducing the air into the building. The premise is that you cannot bring in dirty outside air to dilute dirty inside air. If dilution is used than the clean air should be introduced. Camfil Farr Technical Bulletin, Air Filtration for Improved Indoor Air Quality synopsizes the Indoor Air Quality Method.
The pollutant levels defined in the NAAQS are also used as an evaluation as to the cleanliness of a building's indoor air.
The basis for using the NAAQS as a determination of air quality is defined in Standard 62, Ventilation for Acceptable Indoor Air Quality as published by the American Society of Heating Refrigeration and Air Conditioning Engineers. The Standard also offers an Indoor Air Quality Method that allows the use of air cleaning to simulate the use of clean outside air.
The National Ambient Air Quality Standards defines six principal pollutants, which are called "criteria" pollutants. They are listed below. Units of measure for the standards are parts per million (ppm) by volume, milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air (µg/m3).
National Ambient Air Quality Standards
| POLLUTANT |
STANDARD
VALUE * |
STANDARD
TYPE |
Carbon Monoxide (CO) |
| 8-hour Average |
9 ppm |
(10 mg/m3) |
Primary |
| 1-hour Average |
35 ppm |
(40 mg/m3) |
Primary |
Nitrogen Dioxide (NO2) |
| Annual Arithmetic Mean |
0.053 ppm |
(100 µg/m3) |
Primary & Secondary |
Ozone (O3) |
| 1-hour Average |
0.12 ppm |
(235 µg/m3) |
Primary & Secondary |
| 8-hour Average |
0.08 ppm |
(157 µg/m3) |
Primary & Secondary |
Lead (Pb) |
| Quarterly Average |
1.5 µg/m3 |
|
Primary & Secondary |
Particulate (PM 10) Particles with diameters of 10 micrometers or less |
| Annual Arithmetic Mean |
50 µg/m3 |
|
Primary & Secondary |
| 24-hour Average |
150 µg/m3 |
|
Primary & Secondary |
Particulate (PM 2.5) Particles with diameters of 2.5 micrometers or less |
| Annual Arithmetic Mean |
15 µg/m3 |
|
Primary & Secondary |
| 24-hour Average |
65 µg/m3 |
|
Primary & Secondary |
Sulfur Dioxide (SO2) |
| Annual Arithmetic Mean |
0.030 ppm |
(80 µg/m3) |
Primary |
| 24-hour Average |
0.14 ppm |
(365 µg/m3) |
Primary |
| 3-hour Average |
0.50 ppm |
(1300 µg/m3) |
Secondary |
|
| * Parenthetical value is an approximately equivalent concentration. |
To view current EPA statistics relating to your geographic area, CLICK HERE.
Camfil Farr publishes a complete technical bulletin on how to use filtered recirculated air as opposed to bringing in outside air. The bulletin is based upon using the Indoor Air Quality Method as prescribed in ASHRAE Standard 62. The three advantages to using the Indoor Air Quality Method are:
1) Cooling and heating loads are reduced because ventilation air rates are reduced resulting in lower energy expenditures
2) Contaninants are controlled by air filtration and not affected by changes in environmental conditions
3) Smaller HVAC equipment may be used because heating and colling loads are reduced, less enery, smaller equipment footprint, and lower initial HVAC equipment cost.
For a PDF copy of the Camfil Farr bulletin "Air Filtration for Improved Indoor Air Quality" CLICK HERE. Printed copies are available from literature@camfilfarr.com.
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