On very hot summer days, sunlight and emissions from motor vehicles, lawn mowers, industry, paints, solvents and gasoline fumes combine to create smog. Ground level ozone is the main component of summer smog. While ozone in the upper atmosphere protects us from the sun's harmful rays, ozone at ground level is a public health and environmental concern. The central Puget Sound region's smog levels increase when temperatures reach the upper 80s or higher and winds are light. Ozone forms on hot summer days in a complex reaction of sun, heat and emissions from paints, gasoline fumes, industry- but mostly vehicles and other engines.
Regional growth means more people are driving more miles.
During prolonged heat spells, the Puget Sound Clean Air Agency closely monitors air quality. A Smog Watch is implemented to prevent the region from reaching smog levels that exceed federal health standards. The primary goal of a Smog Watch is to reduce air pollution during the heat of the day. Since most of the problem is driven by vehicle emissions, alternatives to driving on those few hot days is key. Avoid driving during a Smog Watch, especially between the hours of 7 am and 3 p.m. Carpool or take the bus.