Air Quality Planning and Information


The US Environmental Protection Agency (US EPA) has established National Ambient Air Quality Standards (NAAQS) for six criteria pollutants, which are known to be harmful to human health and welfare. These criteria pollutants are:

  • carbon monoxide (CO) 
  • lead (Pb)
  • nitrogen dioxide (NO2)
  • ozone (O3)
  • particulate matter (PM) 
  • sulfur oxides (SOx)

The Sacramento Region is currently designated nonattainment for the following criteria pollutantsozone and particulate matter. The Sacramento Region currently meets the NAAQS for carbon monoxide, nitrogen dioxide, sulfur dioxide, and lead.

The federal Clean Air Act (CAA) requires plans which identify how nonattainment areas will attain and/or maintain the NAAQS. The CAA requires the US EPA to review each plan and any plan revisions and to approve the plan or plan revisions if consistent with the CAA.

Key elements of these plans include emission inventories, emission control strategies and rules, air quality data analyses, modeling, air quality progress and attainment or maintenance demonstrations.


Ozone (O3) is a gas composed of three oxygen atoms. It is not usually emitted directly into the air. Generally ozone is created by a chemical reaction between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight.

Ozone is a strong irritant that adversely affects human health. Breathing air containing ozone can reduce lung function and increase respiratory symptoms, thereby aggravating asthma, bronchitis, or other respiratory conditions including chest pains and wheezing. Both short-term and long-term exposure to ozone can irritate and damage the human respiratory system, resulting in:

  • increased susceptibility to respiratory infections. 
  • increased risk of cardiovascular problems such as heart attacks and strokes.
  • increased doctors' visits, hospitalizations, and emergency room visits.
  • increased school absenteeism; and 
  • an increase in mortality/premature deaths, especially in people with heart and lung disease.

The adverse effects of ozone are not just limited to humans. Ozone can also cause damage to crop and natural vegetation by acting as a chemical oxidizing agent. Ground-level ozone is one of the air pollutants regulated by the federal and state government. Many parts of California, including Sacramento County, violate federal ozone health standards. Reducing ozone to levels below state and federal standards is one of the primary goals of the air districts.

The Sacramento region is designated a nonattainment area for the federal 8 hour standard ozone air quality standard. We are required to undertake planning efforts to reach this health-based standard. The region includes all of Sacramento and Yolo counties and portions of Placer, El Dorado, Solano, and Sutter counties.

Particulate Matter

Particulate matter (PM) is a mixture of solid and liquid particles.  Because particles originate from a variety of activities and processes, their chemical and physical compositions vary. PM can be directly emitted or can be produced by secondary formation in the atmosphere when gaseous pollutants, such as nitrogen oxides and sulfur dioxide, chemically react with ammonia and other compounds to form fine aerosol particles.

Sources of PM are mainly due to human (anthropogenic) activities caused by area-wide sources, such as residential wood and other fuel combustion smoke and other pollutants, motor vehicles including entrained road dust and exhaust, and off-road mobile sources including dust and equipment exhaust emissions from construction and farming activities.  PM can also be generated from natural sources such as windblown dust and wildfires.  

Adverse health effects related to particulate matter exposure result in a number of economic costs and social consequences.  These include increased medical costs, hospital admissions, work loss days, school absences, caregiver burdens, and premature deaths.  Numerous scientific studies have linked particle matter exposure to a variety of health-related problems, such as irritation of the airways, coughing, or difficulty breathing, decreased lung function, aggravated asthma, development of chronic bronchitis, irregular heartbeat, and nonfatal heart attacks. People with heart or lung diseases, children and older adults are the most likely to be affected by particle pollution exposure. Studies also indicate that even healthy individuals may experience temporary symptoms from exposure to elevated levels of particle matter.


Thank you for working with us to improve air quality!