There are many sources of air pollution, which all fall under the light blue “Outdoor Air Pollution” in the diagram above. Together, their combined impacts can be referred to as “Cumulative Air Impacts.” Our current and past air monitoring measures the accumulation of all sources and types of outdoor air pollution. (Indoor air pollution is covered by local and state health jurisdictions.) Our studies have shown two main health impacts from air pollution in our region: cardiovascular and respiratory (heart and lung) and cancer risk. Given that many lifestyle and other factors contribute to these risks, outdoor air pollution contributes a small fraction (less than 5%) of all cancers and heart and lung disease^1,2.

While air pollution can pose health impacts beyond heart, lung, and cancer risks, the air pollution levels in our region are below current health thresholds of concern for other types of health outcomes (e.g. developmental, neurological, etc.). Because of this, we’ve prioritized our focus on pollutants that contribute to cardiovascular, respiratory, and cancer health outcomes.

Cumulative Cardiovascular Risks from Air Pollution 

About 90% of our cardiovascular risks from air pollution come from fine particles (see more detail here). We work to reduce and communicate the leading sources of fine particles, which include wood smoke, wildfire smoke, and transportation emissions. Industry is a smaller contributor; even in industrial areas, industry contributes less than the other leading sources to the overall amount of fine particles. We work with industry to comply with regulations through our inspection, permitting, and complaint response programs.

Cumulative Cancer Risks from Air Pollution 

In our region, about 80% of our potential cancer risk from air pollution is from diesel exhaust, specifically diesel particles, also known as diesel particulate matter (DPM). Diesel pollution comes from diesel-fueled trucks, cars, buses, construction equipment, rail, marine, and port activities and is a part of “transportation pollution”. The next highest potential cancer risk is hexavalent chromium, a harmful chemical, which accounts for approximately 5% of the cancer risk from air pollution. Hexavalent chromium is mostly found in industrial areas in our region. The remaining cancer risk mostly comes from other transportation sources and wood smoke.

Exposure Inequity 

Transportation pollution, which includes diesel exhaust and fine particle pollution, is a major contributor to the cumulative risk from air pollution. Transportation pollution is also the most important contributor to inequality from air pollution in our region. Overburdened communities—communities already disproportionally impacted by a number of factors—often live near major roadways and ports, and local and national studies have shown people of color and lower income communities have higher exposure to transportation pollution.

To help identify areas where there may be air quality inequity, we developed the Community Air Tool. This interactive map helps us discover communities in the Puget Sound region that have a combination of nearby air pollution sources, poorer health, and socioeconomic barriers.

More Information

You can find more information about cumulative impacts in our region here: 

• Cumulative Impacts – Monitoring
• Cumulative Impacts – Community Air Tool