To protect human health, National Ambient Air Quality Standards are established for six Criteria Air Pollutants. Of these six, there are two of most concern in the Spokane region: Fine Particulate (PM2.5) and Ozone (key component of smog).
Particle matter includes two pollutants that are defined by size: Fine particles are 2.5 microns in diameter and smaller (combustion-related) and coarse particles are 10 microns in diameter and smaller (e.g. includes larger particles such as dust.) In the past, the Spokane-area did not meet the health-based standards for PM10. Since 2005, the area has been in compliance with the standards, mainly as a result of improved street cleaning practices, better traction sand, and the introduction of liquid de-icing used in conjunction with traction sand.
Numerous scientific studies have linked exposure to these tiny particles - approximately 1/30th the size of a human hair - with serious human health problems including premature death in people with heart and lung disease; nonfatal heart attacks; and increased hospital admissions and doctor and emergency room visits for respiratory and cardiovascular disease.
Spokane’s fine particle pollution comes from a variety of combustion sources, including industrial operations, motor vehicles, indoor wood heating, outdoor burning and wildfires.
Historical data for PM2.5:
Ozone (O3) - Unlike ozone that is present in the 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. Ozone is only a concern during the hot, summer months when levels can pose a health concern. Ozone trends chart
Even at low concentrations, ozone causes respiratory problems and aggravates asthma in children. People with respiratory diseases and those who work or exercise outside should limit their time outdoors on hot, sunny days when ozone levels are likely to be elevated.
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.
Ozone-forming emissions come from many sources including motor vehicles, industrial solvents, gasoline refueling, gasoline-powered yard equipment, auto body paint shops, and consumer products such as charcoal lighter fluid, paints, etc. Some studies suggest wildfires can impact ozone levels in some areas of the country; this has not been studied in the Spokane area.
In addition to criteria pollutants, there is a category of pollutants called air toxics that includes over 400 pollutants known or suspected to cause cancer or other serious health problems. Air toxics include diesel soot, benzene, polycyclic aromatic hydrocarbons (tar-like byproducts from auto exhaust, wood burning and other sources) metals, etc. Air toxics come from a variety of sources including cars and trucks, all types of burning, business/industrial activities and consumer products. Air toxics Community Assessment 2005 study findings.
The Washington State Department of Ecology conducts a comprehensive Emissions Inventory for the state every three years, which includes detailed information about emissions of pollutants for specific source categories (e.g. railroads or outdoor burning) by county.
Click here for seasonal air quality concerns and actions that individuals can take to help the air we share.