Multiple news outlets reported Thursday that San Francisco has (or had) the worst air quality worldwide thanks to the constant smoke haze drifting over the Bay Area from the Camp Fire in Butte County.
A chart credited to the commercial air monitor company AirVisual’s app ranked San Francisco air as the worst worldwide on Thursday evening, with an Air Quality Index score of 274. Second place Delhi, India, was 268 at the time.
However, according to the Bay Area Air Quality Management District [BAAQMD], the public body that monitors and regular air pollution in San Francisco, SF’s bad air index topped out at 245 on Thursday.
In fact, a handful of other Bay Area cities—Berkeley, Oakland, San Pablo—at least briefly recorded worse scores during the day. San Pablo’s high of 263 was the worst in the region.
Curbed SF asked BAAQMD spokesperson Kristine Roselius to clear up this discrepancy.
“You are right to be skeptical,” says Roselius. “We’re seeing the highest [index scores] in Chico and Sacramento, near the fire.”
“Some news outlets here are lumping it all into saying that the worst AQI in the world right now is in Northern California, and I guess that would be correct,” notes Roselius.
But not so for just San Francisco itself.
Bill Magavern, spokesperson for the Coalition For Clean Air, agrees.
“I’m sitting in Sacramento right now,” Mavagern tells Curbed SF. “We know the air in SF is really bad, I wouldn't want to downplay that in any way. But we do know that it is worse in the Sacramento Valley.”
Mavagern says commercially available air monitors like AirVisual and competitor PurpleAir are pretty reliable but also says that he’s observed PurpleAir devices measuring consistently higher AQI rates than government monitors, which he says are generally more accurate.
(AirVisual and PurpleAir have not yet returned requests for comment on how their SF data compares to figures from Sacramento or Butte County.)
Is it plausible for quirky weather patterns to perhaps briefly shift in such a way that a city like Chico—just a few miles from the perimeter of the Camp Fire—might actually be better off air-wise than the Bay Area?
“Wildfire smoke is really unpredictable,” concedes Roselius. “But those are huge hypotheticals.”
And such a scenario would not last long even if it did come up.
[Update: Jason Mandly, Senior Planner for the Butte County Air Quality Management District, tells Curbed SF that sometimes outlying regions actually can suffer worse atmospheric effects from a fire compared to areas closer to the burn, and that this happened the first day of the Camp Fire.
But Mandly also says that the past 48 hours conditions in Butte County have been much worse than in the Bay Area.
Mandly says that while PurpleAir equipment is generally good—”We check it sometimes to get the lay of things”—he also speculates that at higher ranges of the AQI spectrum their margin of error may increase, although confirming that would require further testing.]
In short, while the rate of particulate matter in the air across Northern California is changing all the time—and although both fire and weather are full of unfortunate surprises—it’s not plausible to imagine that San Francisco has the worst air quality in California, much less the world.
However, that’s no reason to imagine that this means the current toxic air conditions in the city should not be taken seriously.
That 245 Thursday high in SF was the highest BAAQMD has recorded since it began monitoring in 2000.
“Readings above 200 have not occurred in the Bay Area in decades,” notes BAAQMD’s site.
The Environmental Protection Agency classifies current air conditions throughout the Bay Area as “unhealthy” or “very unhealthy.”
San Franciscans should respond accordingly by keeping indoors as much as possible, buying and wearing N95 masks when out, and avoiding physical exertion as much as possible. This goes double for children, the elderly, and those suffering from preexisting health issues.
[Update: Asked about the “worst in the world” qualifier, EPA spokesperson Nahal Mogharabi told Curbed SF, “Unfortunately, EPA doesn’t have enough air quality data on the world to confirm that” one way or the other.
The EPA’s own air quality monitoring data does still reflect worse conditions in Sacramento and Butte County than in San Francisco though. Chico’s AQI score as of 2 p.m. Friday is 437.]