November 1998 Air Quality Report

• Weather patterns affecting air quality
• Highest monitored levels of air pollution
• Highest levels of particulate matter (PM10 & PM2.5), carbon monoxide (CO), and ozone (O3)

Excellent pollutant dispersion generally prevailed during November. Precipitation was above normal across the entire state, and was the wettest November on record for SeaTac airport, which received 199% of normal rainfall for November. The airport average monthly temperature of 46.7 degrees F was 1.4 degrees above normal for November with a maximum temperature of 57ºF on the 15th and a minimum temperature of 36ºF on the 7th.

• The highest PM10 value of 42 µg/m³ was in the "Good" category (PSI of 42) and was measured on Saturday the 7th at the Puyallup South Hill site. The highest PM2.5 value of 34 µg/m³ was in the "Moderate" category (proposed PSI of 64) and was measured on Sunday the 8th at the Meadowdale site in Kitsap County.
• The highest 8-hour average for carbon monoxide was 4.9 ppm, in the "Moderate" category (PSI of 54), and occurred during the evening hours of Monday the 2nd at the Univeristy District site in Seattle.
• The worst visual range of 8.5 miles occurred the evening of Saturday the 28th from 9:00-10:00 pm PST at the Lake Forest site.

Puget Sound Air Pollution Control Agency