Ninety-nine percent of Oregonians currently live where the air meets national health standards. That's a dramatic change from 1980 when only 30 percent of Oregonians lived in clean air areas. This improvement is attributed to DEQ's air pollution prevention programs. The Portland and Rogue Valley areas have the most problems. This is attributed to population and economic growth.
Motor vehicles are the largest source of air pollution in Oregon.
Smog and carbon monoxide are problems in the Portland area and the Rogue Valley. Most of Oregon's air pollution is caused by individual actions such as driving cars, using woodstoves, gas-powered yard equipment and boat motors, paints and aerosol products like hair spray and air fresheners, and outdoor burning. In the Portland-Metro area, all 1975 model year vehicles and newer must be tested. In the Medford area, all 1980 model year vehicles and newer must be tested. Cars, truck, vans, motor homes, and buses powered by gasoline or alternative fuels, such as propane or diesel, with manufacturer's gross weight rating of 8,500 pounds or less must be tested.