Thanks to mild summer weather, with onshore breezes and few hot days, the Bay Area experienced one of its cleanest ozone seasons. During the smog season, from June 1 to October 15, the Bay Area Air Quality Management District (Air District) called only 5 Spare the Air advisories, on days when it expected that air pollution would reach unhealthful levels.
This year, the national 1-hour ozone standard of 12 parts per hundred million (pphm) was exceeded on 3 days, on June 14 and 15 and July 31, the same number of exceedances as in 1999. The state ozone standard of 9 pphm was reached on 12 days, compared with 20 days in 1999. The new national 8-hour average ozone standard of 8 pphm was exceeded on 4 days, compared with 9 days in 1999.
On Spare the Air days, people are asked to curtail their driving and other air polluting activities. An e-mail survey by the Air District showed that 37.5 percent of those surveyed reduced their driving or did not drive for air quality reasons. Of this group, 12.5 percent worked at home or telecommuted, 19.5 percent switched to public transit, and 13.5 percent used carpools or vanpools.
The wintertime Spare the Air Tonight Program alerts people to evenings when air pollution levels are expected to be high and asks that woodburning stoves and fireplaces not be used.