General Information on Air Contaminants

Why does SWCAA regulate air contaminant emissions?

SWCAA regulates air contaminant emissions in order to keep our air clean and healthy. Prolonged exposure to certain air contaminants has been shown to adversely impact human health. In addition, high levels of air contaminants can cause crop damage and deterioration of natural resources. SWCAA's regulations, policies, and programs are designed to maintain air quality standards, protect human health, prevent injury to plant and animal life, and protect the area's scenic views for current and future generations.

What authority does SWCAA have to regulate air contaminant emsissions

SWCAA's legal authority can be found in the Washington Clean Air Act (RCW 70.94). SWCAA's regulatory authority has been directly delegated by the U.S. Environmental Protection Agency [U.S. Clean Air Act (42 USC 7401 et seq.)] and the Washington State Department of Ecology. SWCAA has adopted regulations for the control of air contaminant emissions, including toxic air contaminants, substances for which primary and secondary National Ambient Air Quality Standards (NAAQS) have been established, and volatile organic compounds.

Where do air contaminants come from?

Air contaminants are emitted from a wide variety of sources in southwest Washington.  Sources are often lumped into three broad categories, point sources, area sources and mobile sources.  Point sources are traditionally stationary facilities like factories.  Mobile sources represent motor vehicles of all types.  Area sources are widely dispersed and often non-regulated and non-controlled.  Dry cleaning, painting operations, outdoor burning, gasoline lawn movers, and biogenic sources such as forest and brush fires are some examples.

What air contaminants are SWCAA concerned with?

SWCAA is concerned with particulate matter (PM), particulate matter small than 10 microns (PM10), carbon monoxide (CO), ozone (O3), volatile organic compounds (VOCs), nitrogen oxides (NOx), sulfur dioxide (SO2), lead as well as toxic and hazardous air pollutants (TAPS and HAPs).

PM and PM10 are emitted from both natural and anthropogenic sources such as traffic, industry, combustion, mineral crushing and other human activities.  Particles less than 10 microns in size are of greatest concern because they can be inhaled past the nose and mouth and may penetrate deeply into the lungs.

CO is a colorless, odorless, poisonous gas.  In the body, CO binds tightly to hemoglobin (the red pigment in the blood that moves oxygen from the lungs to the rest of the body).  Once hemoglobin is bound to CO it can no longer carry oxygen.  In this way, CO reduces the oxygen-carrying capacity of the blood and can result in adverse health effects.  The major human caused source of CO is incomplete combustion of carbon based fuels.  This is primarily from gasoline powered motor vehicles.  Other important sources are wood stoves, outdoor burning, and fuel combustion in industrial and utility boilers.

Ozone is a pungent, toxic, highly reactive form of oxygen.  It causes irritation of the nose, throat, and lungs.  Exposure to ozone can cause increased airway resistance and decreased efficiency of the respiratory system.  Ozone is not emitted directly into the air.  It is formed through a series of photochemical reactions between other pollutants (mainly VOC and NOx) and oxygen.  To control ozone pollution, it is most common to control both VOC and NOx.

VOCs (Volatile Organic Compounds) include a large family of compounds made up of hydrogen and carbon.  These compounds are instrumental in the complex series of reactions leading to the formation of ozone and photochemical fog.  These compounds come primarily from motor vehicles, fuel evaporation, industrial coatings and combustion processes.

NOx (NO2 and NO) is a reddish-brown gas that is toxic in high concentrations.  It is a lung irritant and may be related to chronic pulmonary fibrosis.  It is also important in the photochemical reactions leading to the formation of ozone.  It can cause indirect damage to materials when it combines with moisture in the air to form nitric acid.  Nitric acid can then cause corrosion of metal surfaces and can also contribute to acid rain.  In addition it absorbs visible light and causes reduced visibility.  The major human caused source of NOx is fuel combustion in motor vehicles and utility and industrial boilers.

SO2 is a colorless, pungent, nonflammable gas.  In the body it acts as a lung and eye irritant.  When SO2 is inhaled it causes bronchial constriction which results in breathing difficulty and an increase in pulse and respiratory rate.  SO2 can also react in the atmosphere to create sulfuric acid, which can lead to severe respiratory problems.  SO2 is emitted into the atmosphere through the combustion of sulfur containing fossil fuels.  In the US more than half is emitted by power generating plants.

Lead is a toxic heavy metal.  High concentrations of lead in the blood can cause severe and permanent brain damage, especially in children.  Damage can also be caused to the heart, kidney, liver, and nerve and blood tissues.  The major source of lead in the air was the combustion of leaded gasoline in automobiles.  This source accounted for close to 90 percent of the total emissions annually.  Emissions have sharply decreased since the banning of leaded gasoline.