The push of marine air that cooled the region down overnight has provided a temporary improvement to the area’s smoggy air. However, with temperatures forecast to increase again over the weekend as a stagnant weather pattern redevelops, Puget Sound Clean Air Agency staff expect ozone pollution (smog) to again reach the “Unhealthy for Sensitive Groups (USG)” category in many communities of the Cascade foothills.

Clean Air Agency forecasters say air quality on Friday will be “Good” in most areas of the Puget Sound region, yet still rising to “Moderate” levels on the Air Quality Index (AQI) in the Cascade foothills of King and Pierce counties.

Exposure to ground-level ozone can trigger asthma attacks, make breathing difficult, exacerbate lung and heart problems and weaken the immune system. The Washington State Department of Health recommends that people who are sensitive to air pollution limit time spent outdoors.

Air pollution is especially harmful to children, people with heart and lung problems, and adults over age 65.

Smoggy conditions will mostly impact communities in the Cascade foothills of King and Pierce counties. These outlying suburban and rural areas accumulate pollution generated by traffic and activities in the urban areas of Everett, Seattle and Tacoma.

The conditions are expected to persist into mid-week next week. Current ozone levels can be monitored at the Puget Sound Clean Air Agency’s Web site, as can extended forecast information.