Air Quality

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Air Quality

Spokane Air Quality Boundary Map

Carbon Monoxide
Historically, the Spokane County Urban Area has had difficulty maintaining compliance with national ambient air quality standards (NAAQS) for carbon monoxide (CO).

CO is a colorless, odorless gas that reduces the oxygen-carrying capacity of the blood.  Motor vehicle exhaust contributes about 56% of CO emissions nationwide (Environmental Protection Agency Office of Air and Radiation 2004).  CO exposure can lead to chronic health effects and even death at high levels.  Symptoms of CO exposure include headaches, dizziness and nausea.

Since 1999, Spokane has had no recorded violations of the CO standard.  The Environmental Protection Agency (EPA) has re-designated Spokane from a “non-attainment” area to an “attainment” area for CO, currently operating under a Maintenance Plan.  This change in status does not alleviate the area from studying and monitoring both regional and localized CO impacts from transportation projects.  SRTC and other impacted jurisdictions will continue regional and localized transportation conformity analyses until EPA determines appropriate as guided under the CO Maintenance Plan.

The following resources are for SRTC’s partner agencies to use for technical data in preparing localized CO hot-spot analysis: first locate the specific intersection using this air quality map. After locating your intersection use this spreadsheet to determine the background concentration of your project.

What Is A Maintenance Plan?
A maintenance plan is a document that outlines strategies to stay in compliance with air quality standards for the next ten years. The CO motor vehicle emissions budget (MVEB) contained in the Maintenance Plan for the Spokane County Urban Area was determined adequate by EPA and published in a January 28, 2005 Federal Register Notice, becoming effective February 14, 2005. The revised MVEB is 558,000 lbs/day (i.e., 279 tons/day).

In an effort to ensure that transportation projects do not create new CO hotspots, make existing conditions worse, or delay timely attainment of the CO standard, SRTC provides air quality modeling services to local jurisdictions and agencies using EPA approved models and procedures.

Particulate Matter
Particulate Matter (PM) is the term for particles found in the air, such as dust, dirt, soot, smoke and liquid droplets (EPA Office of Air and Radiation 2004).  Particles come in almost any shape or size.  Particles are divided into two major groups; the larger particles are called PM10 and the smaller particles PM2.5

The big particles are between 2.5 and 10 micrometers (from about 25 to 100 times thinner than a human hair).  These particles cause less severe health effects.  The smaller particles are smaller than 2.5 micrometers (100 times thinner than a human hair) and are generally more toxic.  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 from unpaved roadways, construction activities, gas and diesel powered engines, wood burning, outdoor burning and industrial/commercial operations.  High PM concentrations occur in fall and winter during stagnant air periods and the increased use of wood for heating.  PM can be suspended and carried in the air for long periods of time and over long distances.  Click on the link see a Chart of the monitored PM10 data.

Ground-level Ozone
In our region, ground-level ozone is considered a summertime pollutant. The hot sunny days of summer contribute to the formation of ground-level ozone, a harmful pollutant and key ingredient in smog. Ozone is formed when nitrogen oxides and volatile organic compounds react in the presence of sunlight. Pollutants from daily activities, such as refueling and driving cars, using gas-powered lawn equipment, and using industrial and household solvents, “cook” in the hot temperatures, forming ground-level ozone. Ozone concentrations typically peak on calm, 90+degree days.

When inhaled, ozone can cause coughing, throat irritation, and pain when breathing deeply. It can also reduce lung function, inflame the lining of the lungs, and trigger asthma attacks. Repeated inflammation over time may permanently scar lung tissue. Your chances of being affected by air pollution increase the longer you are active outdoors or the more strenuous the activity. Kids and teens who are active outdoors, especially those with asthma or other respiratory problems, are particularly sensitive.

The current Ozone standard is 0.075 parts per million (ppm), averaged over 8 hours. Ozone levels are monitored in the Spokane area and, thus far, have measured within the current standards.  Click on the link to view a Chart of the monitored Ozone data

Partner Agencies for Air Quality: 

Spokane Regional Clean Air Agency
Environmental Protection Agency
Washington State Department of Ecology

For more information on Air Quality, please e-mail Anna Ragaza-Bourassa at