|
Table 1. Ambient Air Quality
Standards
|
|
Pollutant |
Averaging Time |
California Standards1 |
National 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 μg/m3)* |
0.075 ppm
(157 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 |
revoked |
|
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 µg/m3 |
|
Carbon
Monoxide (CO)
|
8 Hour |
9.0 ppm
(10 mg/m3)
|
Non-Dispersive
Infrared Photometry
(NDIR) |
9 ppm
(10 mg/m3)
|
Same as Primary Standard |
Non-Dispersive
Infrared Photometry
(NDIR) |
|
1 Hour |
20 ppm
(23 mg/m3)
|
35 ppm
(40 mg/m3)
|
8 Hour
(Lake Tahoe) |
6.0 ppm
(7 mg/m3)
|
-- |
-- |
-- |
|
Nitrogen
Dioxide
(NO2)
|
Annual Arithmetic Mean
|
0.030 ppm
(56 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
(338 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)
|
-- |
-- |
-- |
|
Lead9 |
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 |
|
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 (4/1/08)
Notes:
- 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.
- 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 µg/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.
- 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.
- 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.
- National Primary Standards: The levels of air quality
necessary, with an adequate margin of safety to protect the public health.
- National Secondary Standards: The levels of air quality necessary to
protect the public welfare from any known or anticipated adverse effects of
a pollutant.
- 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.
- 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.
California Air Resources Board (4/1/08)
Download this table in a printable PDF format:
standards.pdf
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