San Francisco skies finally clear again

Consecutive days of rain (with more in the forecast) have rejuvenated San Francisco’s atmosphere, which, just one week ago, registered all-time worst levels of air pollution thanks to the nearly contained Camp Fire to the northeast, but now is back to its crystal clear self.

According to the Environmental Protection Agency’s [EPA] AIRNow site, the city’s Air Quality Index [AQI] crept as high as 50 on Thursday—the highest figure that can still be considered “good” on the physician-designed AQI scale—but by and large remained well below that mark all day.

A burst of “moderate” quality air floated over the furthest ends of the East Bay early Thursday but quickly dissipated; in short, the air is once again some of the best worldwide, a 180-degree turnaround from seven days ago.

Friday’s forecast calls for much the same in the city and most of the region, although air in the North Bay and parts of the East Bay will be only “moderate.”

To get an idea of how unprecedented the bad air spell was, City Hall’s “performance scorecard” page records air quality history going all the way back to 2000.

In 2017, SF had 276 days of “good” air quality and just 82 days where the AQI rose to “moderate” levels of pollution.

Courtesy SF City Hall

Data for previous years looks even better; you have to go all the way back to 2002 for anything close to the “unhealthy” grade.

Spokespersons for the Bay Area Air Quality Management District [BAAQMD] tell Curbed SF that last week’s figures—which rose as high as 245 AQI on the worst days—are essentially unprecedented.

Although BAAQMD and other air-monitoring agencies tell Curbed SF that the smoky air posed relatively little risk to healthy individuals in the sort run, weeks of bad air created pronounced public anxiety.

After years of wildfires, drought, and climate change ravaging California, the crisis hit San Francisco in a dramatic physical manifestation that nobody could ignore.

Although the Butte County Camp Fire that created the smoggy skies in the first place is almost fully contained as of Friday morning, it will continue to smolder for some time. Additional risk to public health from invading smoke is still possible.

• AIRNow Forecast SF [EPA]
• SF AQI Index [City of SF]