Table 1. Ambient Air Quality Standards

Pollutant

Averaging Time

California Standards1

Federal Standards2

Concentration3

Method4

Primary3, 5

Secondary3, 6

Method7

Ozone (O3)

1 Hour

0.09 ppm (180 µg/m3)

Ultraviolet Photometry

Same as Primary Standard

Ultraviolet Photometry

8 Hour

0.070 ppm (137 ?g/m3)*

0.075 ppm (147 µg/m3)

Respirable Particulate Matter (PM10)

24 Hour

50 µg/m3

Gravimetric or Beta Attenuation

150 µg/m3

Same as Primary Standard

Inertial Separation and Gravimetric Analysis

Annual Arithmetic Mean

20 µg/m3

Fine Particulate Matter (PM2.5)

24 Hour

No Separate State Standard

35 µg/m3

Same as Primary Standard

Inertial Separation and Gravimetric Analysis

Annual Arithmetic Mean

12 µg/m3 Gravimetric or Beta Attenuation

15.0 µg/m3

Carbon Monoxide (CO)

8 Hour

9.0 ppm (10 mg/m3)

Non-Dispersive Infrared Photometry (NDIR)

9 ppm (10 mg/m3)

None

Non-Dispersive Infrared Photometry (NDIR)

1 Hour

20 ppm (23 mg/m3)

35 ppm (40 mg/m3)

8 Hour (Lake Tahoe)

6 ppm (7 mg/m3)

Nitrogen Dioxide (NO2)

Annual Arithmetic Mean

0.030 ppm (57 µg/m3)

Gas Phase Chemi-luminescence

0.053 ppm (100 µg/m3)

Same as Primary Standard

Gas Phase Chemi-luminescence

1 Hour

0.18 ppm (339 µg/m3)

Sulfur Dioxide (SO2)

Annual Arithmetic Mean

Ultraviolet Fluorescence

0.030 ppm (80 µg/m3)

Spectro-photometry (Pararosaniline Method)

24 Hour

0.04 ppm3(105 µg/m3)

0.14 ppm (365 µg/m3)

3 Hour

0.5 ppm (1,300 µg/m3)

1 Hour

0.25 ppm (655 µg/m3)

Lead8

30 Day Average

1.5 µg/m3

Atomic Absorption

 

Calendar Quarter

1.5 µg/m3

Same as Primary Standard

High Volume Sampler and Atomic Absorption
Rolling 3-month Average9 0.15 µg/m3

Visibility Reducing Particles

8 Hour

Extinction coefficient of 0.23 per kilometer ? visibility of ten miles or more (0.07 ? 30 miles or more for Lake Tahoe) due to particles when relative humidity is less than 70 percent. Method: Beta Attenuation and Transmittance through Filter Tape.

No Federal Standards

Sulfates

24 Hour

25 µg/m3

Ion Chromatography

Hydrogen Sulfide

1 Hour

0.03 ppm (42 µg/m3)

Ultraviolet Fluorescence

Vinyl Chloride8  

24 Hour

0.010 ppm (26 µg/m3)

Gas Chromatography
California Air Resources Board (11/17/08)

Notes:

  1. California standards for ozone, carbon monoxide (except Lake Tahoe), sulfur dioxide (1 and 24 hour), nitrogen dioxide, suspended particulate matter?PM10, PM2.5, and visibility reducing particles, are values that are not to be exceeded. All others are not to be equaled or exceeded. California ambient air quality standards are listed in the Table of Standards in Section 70200 of Title 17 of the California Code of Regulations.
  2. National standards (other than ozone, particulate matter, and those based on annual averages or annual arithmetic mean) are not to be exceeded more than once a year. The ozone standard is attained when the fourth highest eight hour concentration in a year, averaged over three years, is equal to or less than the standard. For PM10, the 24 hour standard is attained when the expected number of days per calender year with a 24-hour average concentration above 150 ?g/m3 is equal to or less than one. For PM2.5, the 24 hour standard is attained when 98 percent of the daily concentrations, averaged over three years, are equal to or less than the standard. Contact U.S. EPA for further clarification and current federal policies.
  3. Concentration expressed first in units in which it was promulgated. Equivalent units given in parentheses are based upon a reference temperature of 25°C and a reference pressure of 760 torr. Most measurements of air quality are to be corrected to a reference temperature of 25°C and a reference pressure of 760 torr; ppm in this table refers to ppm by volume, or micromoles of pollutant per mole of gas.
  4. Any equivalent procedure which can be shown to the satisfaction of the ARB to give equivalent results at or near the level of the air quality standard may be used.
  5. National Primary Standards: The levels of air quality necessary, with an adequate margin of safety to protect the public health.
  6. National Secondary Standards: The levels of air quality necessary to protect the public welfare from any known or anticipated adverse effects of a pollutant.
  7. Reference method as described by the EPA. An ?equivalent method? of measurement may be used but must have a ?consistent relationship to the reference method? and must be approved by the EPA.
  8. The ARB has identified lead and vinyl chloride as ‘toxic air contaminants’ with no threshold level of exposure for adverse health effects determined. These actions allow for the implementation of control measures at levels below the ambient concentrations specified for these pollutants.
  9. National lead standard, rolling 3-month average: final rule signed October 15, 2008.

California Air Resources Board (11/17/08) | For more information please call ARB-PIO at (916) 322-2990


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