Meeting Air Quality Standards

In February 2022, the California Air Resources Board took action at a public hearing to change Santa Barbara County’s designation from “unclassified” to “attainment” for the State PM2.5 standard, based on data measured in the County for the 3-year period from 2018 to 2020. The designation change became effective on October 10, 2022 when the California Office of Administrative Law (OAL) reviewed and approved the CARB rulemaking action.

Air quality standards define clean air. They tell us how much of a substance can be in the air without causing harm, based on proven scientific and medical research. Both the federal and state governments set air quality standards. In most cases, California’s standards are more health-protective than the federal standards.

Federal standards have been established for seven pollutants:

  1. Ozone,
  2. Nitrogen Dioxide,
  3. Sulfur Dioxide,
  4. Carbon Monoxide,
  5. Particulate Matter less than 10 microns in diameter (PM10),
  6. Particulate Matter less than 2.5 microns in diameter (PM2.5), and
  7. Lead.

California standards exist for all of the pollutants above, plus four more:

  1. Sulfates,
  2. Hydrogen Sulfide,
  3. Vinyl Chloride (chloroethene), and
  4. Visibility Reducing Particles.

These are the only pollutants – out of hundreds in our air – for which standards have been set. These pollutants were chosen because they are commonly emitted from numerous sources and they are considered harmful to both human health and the environment.

The Attainment Designation tells us whether our air meets the health-based standards. Santa Barbara County is attainment/unclassified for all federal ambient air quality standards, including the 2015 revision to the federal 8-hour ozone standard. However, the County is currently nonattainment for the state ozone standard and the PM10 standard. See the Table below for a full listing of the attainment status for each pollutant.

Other Resources:

Santa Barbara County Attainment & Nonattainment Designations

Averaging Time
California Standards
National Standards
Pollutant ConcentrationAttainment DesignationPollutant ConcentrationAttainment Designation
8 hour0.070 ppmN0.070 ppmA/U
1 hour0.09 ppmRevoked
Nitrogen Dioxide
annual arithmetic mean0.030 ppm
(56 µg/m3)
A0.053 ppm
(100 µg/m3)
1 hour0.18 ppm
(338 µg/m3)
0.10 ppm
(188 µg/m3)
Sulfur Dioxide
24 hour0.04 ppm
(105 µg/m3)
1 hour0.25 ppm
(655 µg/m3)
0.075 ppm
(196 µg/m3)
Carbon Monoxide
8 hour9.0 ppm
(10 mg/m3)
A9 ppm
(10 mg/m3)
1 hour20 ppm
(23 mg/m3)
35 ppm
(40 mg/m3)
Particulate Matter (PM10)
annual arithmetic mean20 µg/m3NRevoked
24 hour50 µg/m3150 µg/m3U
Particulate Matter (PM2.5)
annual arithmetic mean12 µg/m3A12.0 µg/m3A/U
24 hour35 µg/m3A/U
Rolling 3-month average0.15 µg/m3A/U
30 day average1.5 µg/m3A
24 hour25 µg/m3A 
Hydrogen Sulfide
1 hour0.03 ppm
(42 µg/m3)
Vinyl Chloride (chloroethene)
24 hour0.01 ppm
(26 µg/m3)
Visibility Reducing Particles
8 hour
(1000 to 1800 PST)
 See Note #1U

  A = Attainment; 
  N = Nonattainment; 
  U = Unclassified; 
/U = Attainment/Unclassifiable; 
  — = No Standard

  mg/m3 = milligrams per cubic meter;
  µg/m3 = micrograms per cubic meter;   
  ppm = parts per million;   
  ppb = parts per billion;

Note #1: Statewide VRP Standard (except Lake Tahoe Air Basin): Particles in sufficient amount to produce an extinction coefficient of 0.23 per kilometer when the relative humidity is less than 70 percent. This standard is intended to limit the frequency and severity of visibility impairment due to regional haze and is equivalent to a 10-mile nominal visual range.

Note #2: Recent EPA federal registers have established that the “Attainment/Unclassifiable” designation is clearer than “Unclassifiable/Attainment”, and that re-ordering the terms has no regulatory consequence.