Meeting Air Quality Standards

In February 2021, the California Air Resources Board took action at a public hearing to change Santa Barbara County’s designation from attainment to nonattainment for the State ozone standards. This change was based on data measured at multiple locations in the County for the 3-year period from 2017 to 2019. View the District’s comment letter.
The California Office of Administrative Law (OAL) finalized the designation change on September 27, 2021.

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 Concentration Attainment Designation Pollutant Concentration Attainment Designation
8 hour 0.070 ppm N 0.070 ppm A/U
1 hour 0.09 ppm Revoked
Nitrogen Dioxide
annual arithmetic mean 0.030 ppm
(56 µg/m3)
0.053 ppm
(100 µg/m3)
1 hour 0.18 ppm
(338 µg/m3)
0.10 ppm
(188 µg/m3)
Sulfur Dioxide
24 hour 0.04 ppm
(105 µg/m3)
A Revoked
1 hour 0.25 ppm
(655 µg/m3)
0.075 ppm
(196 µg/m3)
Carbon Monoxide
8 hour 9.0 ppm
(10 mg/m3)
A 9 ppm
(10 mg/m3)
1 hour 20 ppm
(23 mg/m3)
35 ppm
(40 mg/m3)
Particulate Matter (PM10)
annual arithmetic mean 20 µg/m3 N Revoked
24 hour 50 µg/m3 150 µg/m3 U
Particulate Matter (PM2.5)
annual arithmetic mean 12 µg/m3 U 12.0 µg/m3 A/U
24 hour 35 µg/m3 A/U
Rolling 3-month average 0.15 µg/m3 A/U
30 day average 1.5 µg/m3 A
24 hour 25 µg/m3 A
Hydrogen Sulfide
1 hour 0.03 ppm
(42 µg/m3)
Vinyl Chloride (chloroethene)
24 hour 0.01 ppm
(26 µg/m3)
Visibility Reducing Particles
8 hour
(1000 to 1800 PST)
 See Note #1 U

  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 that “Unclassifiable/Attainment”, and that re-ordering the terms has no regulatory consequence.