Program Template photo identifier

Air Quality Program

Criteria Pollutants and Standards

Criteria Pollutants




Health Effects

Carbon Monoxide (CO) An odorless, tasteless, colorless gas which is emitted primarily from any form of combustion. Mobile sources (autos, trucks, buses), Wood stoves, Open burning, Industrial combustion sources. Deprives the body of oxygen by reducing the blood’s capacity to carry oxygen; causes headaches, dizziness, nausea, listlessness and in high doses, may cause death.
Hydrocarbons (HC) Unburned, partially burnt fuel. Mobile sources (autos, trucks, buses), formed by the incomplete combustion of fuel. When combined with sun light produces photo chemical (smog)
Lead (Pb) A widely used metal, which may accumulate in the body. Leaded gasoline, Smelting, Battery manufacturing and recycling. Affects motor function and reflexes and learning; causes damage to the central nervous system, kidneys and brain. Children are affected more than adults.
Ozone (O3) Formed when nitrogen oxides and volatile organic compounds react with one another in the presence of sunlight and warm temperatures. A component of smog. Mobile sources, Industry, Power plants, Gasoline storage and transfer, Paint. Irritates eyes, nose, throat and respiratory system; especially bad for those with chronic heart and lung disease, as well as the very young and old, and pregnant women.
Nitrogen Dioxide (NO2) A poisonous gas produced when nitrogen oxide is a by-product of sufficiently high burning temperatures. Fossil fuel power, Mobile sources, Industry, Explosives manufacturing, Fertilizer manufacturing. Harmful to lungs, irritates bronchial and respiratory systems; increases symptoms in asthmatic patients.
Particulate Matter

PM10 PM2.5

Particles of soot, dust, and unburned fuel suspended in the air. Wood stoves, Industry, Dust, Construction, Street sand application, Open burning. Aggravates ailments such as bronchitis and emphysema; especially bad for those with chronic heart and lung disease, as well as the very young and old, and pregnant women.
Sulfur Dioxide (SO2) A gas or liquid resulting from the burning of sulfur-containing fuel. Fossil fuel power plants, Non-ferrous smelters, Kraft pulp production. Increases symptoms in asthmatic patients; irritates respiratory system.

Air Quality Standards

New standards for particulate matter smaller than 2.5 microns in size (PM2.5) and ozone were adopted by EPA in 1997.


Washington State
  Primary Secondary  
Carbon Monoxide (CO)      
8 - Hour Average 9 ppm 9 ppm 9 ppm
1 - Hour Average 35 ppm 35 ppm 35 ppm
Lead (Pb)      
Quarterly Average 1.5 µg/m3 1.5 µg/m3 No standard
Nitrogen Dioxide (NO2)      
Annual Average 0.053 ppm 0.053 ppm 0.05 ppm
Ozone (O3)      
1 - Hour Average 0.12 ppm 0.12 ppm 0.12 ppm
8 - Hour Average B 0.08 ppm 0.08 ppm No Standard
Particulate Matter (PM10)      
Annual Arithmetic Mean No Standard No Standard 50 µg/m 3
24 - Hour Average 150 µg/m 3 150 µg/m3 150 µg/m3
Particulate Matter (PM2.5)      
Annual Arithmetic Mean 15 µg/m3 15 µg/m3 No Standard
24-Hour 35 µg/m3 35 µg/m3 No Standard
Sulfur Dioxide (SO2)      
Annual Average 0.030 ppm No Standard 0.02 ppm
24 - Hour Average 0.14 ppm No Standard 0.10 ppm
3 - Hour Average No Standard 0.5 ppm No Standard
1 - Hour Average No Standard No Standard 0.40 ppm A
Total Suspended Particulates      
Annual Geometric Mean No Standard No Standard 60 µg/m3
24 - Hour Average No Standard No Standard 150 µg/m3

A 0.25 not to be exceeded more than two times in any 7 consecutive days.

B Eight hour ozone standard went into effect on September 16, 1997.
        But implementation is limited.

  • ppm = parts per million
  • µg/m3 = micrograms per cubic meter
  • Primary standards are listed in this table as they appear in the federal regulations. Ambient concentrations are rounded using the next higher decimal place to determine whether a standard has been exceeded. The data charts in this report are shown with these un rounded numbers.
  • Details of the National Standards are available in 40 CFR Part 50.

EPA Air Quality Standards Link to 40 CFR Part 50