Criteria Pollutants
Criteria pollutants are defined by the U.S. Environmental Protection Agency (EPA) as six important pollutants (carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide). National air quality standards (NAAQS) are established for each of these compounds to set limits for their concentrations in the air. Understanding and monitoring these pollutants helps communities stay informed about air quality, allows for protective health measures, and guides efforts to reduce pollution for a healthier environment.
Criteria Pollutants 101
The six criteria pollutants regulated under the Clean Air Act are:
- Carbon Monoxide (CO) - colorless, odorless gas from combustion
- Lead (Pb) - from ore/metals processing, aviation fuel
- Nitrogen Dioxide (NO2) - from vehicles and power plants
- Ozone (O3) - formed by chemical reactions in sunlight
- Particulate Matter (PM) - fine particles and dust
- Sulfur Dioxide (SO2) - from fossil fuel combustion
Sources of Criteria Pollutants
In Colorado, the primary sources include:
- Motor vehicles and transportation
- Oil and gas extraction and processing
- Power generation facilities
- Industrial manufacturing
- Residential wood burning
- Agricultural operations
- Wildfire smoke (seasonal)
How Do They Impact You?
Criteria pollutant exposure can cause:
- Respiratory issues (asthma, bronchitis)
- Cardiovascular problems
- Reduced lung function in children
- Aggravation of existing conditions
- Reduced visibility and haze
- Damage to crops and vegetation
Sensitive groups include children, elderly, and those with pre-existing respiratory or heart conditions.
How Is Colorado Addressing This?
Through Regulation:
- State Implementation Plans (SIPs) for NAAQS
- Ozone nonattainment area designations
- Vehicle emissions testing programs
- Industrial permitting requirements
Through Monitoring:
- 50+ continuous monitoring stations statewide
- Real-time AQI reporting
- Special studies and research campaigns