SIP Program

What is Arizona’s State Implementation Plan (SIP)?: Page 2 of 2

What does the SIP do for air pollution?

The National Ambient Air Quality Standards (NAAQS) set forth in the Clean Air Act play a key role in the development of air quality laws, regulations, and SIP revisions. The NAAQS set a maximum level for six pollutants, known as “criteria pollutants,” in the ambient air. “Ambient air” is defined as the portion of the atmosphere, external to buildings, to which the general public has access. Criteria pollutants regulated by the Clean Air Act are (in no particular order):


1. Carbon Monoxide (CO)

2. Nitrogen Oxides (NOX)

3. Particular Matter (PM)

4. Sulfur Dioxide (SO2)

5. Ozone (O3)

6. Lead (Pb)

These criteria pollutants are the subject of SIP revisions when EPA updates the national standards. These standards help decrease pollution in the ambient air to protect human health and the environment. The Clean Air Act also mandates other types of plans for pollutants and sources such as:

  • Clean Power Plan 
  • Regional Haze Plan
  • New Source Review 

Learn more about the Clean Power Plan