Updated: Wednesday, October 18, 2017, 11:45 a.m.
Air pollution in Bay Area counties in the past couple of weeks has been the worst since 1999 when officials began collecting data.
Residents in the North Bay are still experiencing the brunt of the pollution because of nearby wildfires in California's wine country. Residents in Napa, Solano and Sonoma counties should try to stay inside buildings with air conditioning. But people in the East Bay and South Bay are not in the clear because the toxic air is creeping all over the region. You can look up your zip code here.
The pollution was so high last week it was comparable to high pollution days in China, says Lisa Fasano at the Bay Area Air Quality Management District.
The worst hour was measured last Tuesday in Napa with an air quality index of 404 for small particulate matter, so high it's off the chart, as you can see below.