Regulated Pollutants

Smog is the general term used to describe a variety of air pollutants, including ground-level ozone (smog's main ingredient), particulate matter, carbon monoxide and nitrogen oxides. It refers to air pollution that is formed when gases from many sources are released into the air and chemically react with each other in sunlight.

Ocean breezes sweep the smog inland toward the mountains where an inversion layer of warm air pushes it down trapping the smog close to the ground where we live and breathe.

Ground-level ozone (O3) is a colorless, odorless pollutant formed by chemical reaction between volatile organic compounds (VOCs) and oxides of nitrogen (NOx) in the presence of sunlight. The primary source of VOCs aid NOx are mobile sources including: cars, trucks, buses, plus agricultural and construction equipment. In contrast, stratospheric ozone in our upper atmosphere, better known as the ozone layer, shields the earth from the suns harmful ultraviolet rays.

Particulate matter (PM) is the term used for a mixture of solid particle, and liquid droplet, found in the air. It originates from a variety of sources, including motor vehicles, power plants, construction activities, soil dust, soot and industrial processes. Course particles (PM10) are generally emitted from sources such as windblown dust, vehicles traveling on unpaved roads, and crushing / grinding operations. Fine particles (PM2.5) can come from fuel combustion (motor vehicles, power generation, industrial facilities) and fugitive dust. PM2.5 is formed primarily in the atmosphere from gases such as sulfur oxides, NOx, and VOCs.

Carbon monoxide (CO) is a colorless, odorless gas by-product of combustion produced primarily by motor vehicle. Burned wood and charcoal also emit carbon monoxide.


Ground-level Ozone

Ozone is a strong irritant that can constrict the airways, forcing the respiratory system to work harder to provide oxygen. It also can cause:

  • Aggravated respiratory diseases such as emphysema, bronchitis and asthma
  • Damage to deep portions of the lungs, even after symptoms such as coughing or a sore throat disappear
  • Wheezing, chest pain, dry throat, headache, or nausea
  • Reduced resistance to infection and increased fatigue

Particulate Matter

A series of scientific studies has linked particulate matter, especially fine particles, with a variety of significant health problems:

  • Aggravated asthma, heart, or lung disease:
  • Respiratory-related hospital admissions and emergency room visits
  • Acute respiratory symptoms, including severe chest pain, gasping, and aggravated coughing
  • Decreased lung function which can be experienced as shortness of breath
  • Chronic bronchitis
  • Premature death

Carbon Monoxide

Carbon monoxide replaces oxygen in the body's red blood cells. People with heart disease are more susceptible to developing chest pains when exposed to low levels of carbon monoxide. Exposure to high levels of carbon monoxide can slow reflexes and cause confusion and drowsiness and result in death in confined spaces (i.e., an enclosed garage) at very high concentrations.

Regulated Pollutant Standards 

Air Quality Frequently Asked Questions

Air Quality Plans