May 1998 Air Quality Report
Here you will find information about:
- Weather patterns affecting air quality
- Highest monitored levels of air pollution
- Highest levels of particulate matter (PM10),
carbon monoxide (CO) and ozone (O3)
Air Quality Report - May 1998
Weather was fairly typical for the month of
May. Dispersion was very good and resulted in good air quality
for most of the month. The first day of the month was still very
hazy from a cloud of particulate caused by dust storms in China.
All of the particulate sites measured their maximum concentration
on Friday the 1st.
- Precipitation was slightly above normal
with Sea-Tac airport receiving 116% of normal rainfall
for May. The airport average monthly temperature of 54.9
degrees F was -0.2 degrees from normal for May with a
maximum temperature of 81° F on
the 1st and a minimum temperature of 41° F on the 16th.
- Preliminary data shows that none of the
air quality measured values exceeded a federal standard
(NAAQS) or reached the Unhealthful category on the
national Pollutant Standards Index (PSI). The highest
pollutant reading was in the moderate category (PSI of
62) and occurred on Friday, the 1st caused by particulate
(PM10). Only
4 days of the month were in the moderate category.
- The highest PM10 value of 73 µg/m3 (PSI of 62) was measured
on Friday the 1st at the Duwamish site in Seattle.
- The highest 8-hour average for carbon
monoxide was 4.6 ppm (PSI of 51) and occurred the morning
of Friday the 22nd at the University district site in
Seattle.
- The highest 8-hour average for ozone was
0.070 ppm (PSI of 58) and occurred the afternoon of
Friday the 1st at the Pack Forest site in La Grande.
Puget
Sound Air Pollution Control Agency