Two-day "smog watch" issued for four counties

A "smog watch" for the next two days has been issued for King, Pierce, Snohomish and Kitsap counties by the Puget Sound Clean Air Agency as hot air creates a temperature inversion trapping pollutants. Residents are asked to limit yardwork and recreation with gasoline-powered equipment.

The agency's Amy Warren said harmful amounts of ozone are often highest in the Cascade foothill areas of Southeast King County and east Pierce County, where pollutants swept from the Seattle-Tacoma area tend to accumulate.

Those rural areas are likely to have a "moderate" pollution level today, falling to "unhealthy for sensitive groups" Wednesday. In Seattle and Tacoma, the pollution level may drop to "moderate" Wednesday. An onshore flow of wind Wednesday evening is expected to improve air quality.

This is the area's first "smog watch" since stricter air-quality standards went into effect in March. People with asthma and those with lung and cardiovascular disease are more at risk.

For more information, see www.pscleanair.org/airq/basics/weather/smog.aspx.