Air Pollutants

Air Pollutants in Spokane

Of the six criteria pollutants, two are of particular concern in Spokane: Ozone (a summertime pollutant) and Particulate Matter. In addition to the criteria pollutants, there is a category of pollutants that fall under the Air Toxics rules. Click here for more information.

Ozone	Particulate Matter PM10	Particulate Matter PM2.5

Ozone (O₃) Unlike ozone that is present in the Earth’s upper atmosphere, ozone at the Earth’s surface is a harmful air pollutant that poses a risk to human, animal and plant life. Ground-level ozone is formed as a result of photo-chemical reactions between nitrogen oxides and volatile organic compounds in the presence of sunlight and heat. Most of the ozone-forming emissions come from many small sources, spread over a wide area. Click here to see a short video on how ozone is formed.

Nearly two-thirds of these emissions come from motor vehicles. Other sources of smog-forming emissions include industrial solvents, gasoline refueling, gasoline-powered yard equipment, auto body paint shops, and consumer products such as charcoal lighter fluid, paints, etc.

Even at low concentrations, ozone causes respiratory problems and aggravates asthma in children, people with respiratory diseases, and even otherwise healthy adults who are working or exercising outside on smoggy days. Children are most at risk from exposure to ozone because they are often active outside during the summer and their lungs are not fully developed. Long-term exposure to ozone may lead to premature aging of the lungs and chronic respiratory illnesses.  For information about ozone, click here.

Particulate Matter (PM) is composed of solid or liquid particles from smoke, dust, and condensing vapors. PM is suspended and carried in the air for long periods of time and over long distances. There are health-based standards for two sizes of particles: PM₁₀--which are particles 10 microns and smaller and PM_2.5--which are particles 2.5 microns and smaller. These microscopic particles travel deep in the lungs, damaging lung tissue and affecting breathing.

Spokane’s PM pollution comes from a variety of sources, including dust stirred up from traveling on unpaved and paved roadways, construction activities, gas and diesel powered engines, wood burning, outdoor burning and industrial/commercial operations.

Diesel PM is produced when an engine burns diesel fuel. Diesel exhaust is a complex mixture of thousands of gases and fine particles that contains more than 40 toxic contaminants. These include many known or suspected cancer-causing substances, such as benzene, arsenic and formaldehyde. It contains other harmful pollutants, including nitrogen oxides (a component of urban smog).

During winter, fine particles (PM_2.5) from wood burning become elevated under strong temperature inversions. Wood smoke is the chief source of air pollution in the Spokane-area during winter.

American Heart Association Scientific Statement: “ The overall evidence is consistent with a causal relationship between PM_2.5 exposure and cardiovascular morbidity and mortality.” (Brook RD, et al. Circulation 2010; 121: 2331-78)

In December 2009 the Washington State Department of Ecology issued a report on fine particles, "Health Effects and Economic Impacts of Fine Particle Pollution in Washington."

Air Emissions Inventory - The Washington State Department of Ecology conducts a comprehensive air emissions inventory for the state every three years. If you are interested in detailed information about emissions for specific source categories (e.g. railroads or outdoor burning) by county, you can find it in the 2005 inventory.

Below are Pie Charts of Sources of PM, Diesel PM, VOC and NOx Emissions. Click on the chart to enlarge view.