Bad air quality returns after brief respite
The relief from smoky air felt early Tuesday in parts of the wildfirebesieged Bay Area didn’t last long: By late morning, air quality had taken a turn for the worse, hitting unhealthy levels again in the East Bay and Peninsula.
In the early hours, the air quality index was moderate, even good, in many areas.
“This morning we had a nice layer of fog … and the deep marine layer is good for fire suppression, and produces better air quality,” said Aaron Richardson, Bay Area Air Quality Management District spokesperson.
But that quickly dissipated as winds began carrying smoke from the CZU Lightning Complex fires from the southwest up into San Mateo and Redwood City, where levels have been firmly in the 150s since this morning.
“Things began heating up and the air quality is getting worse today, as expected,” Richardson said. “The worst pockets seem to be the east side of the Peninsula, in Redwood City and San Mateo, even east San Francisco . ... The East Bay is in the solid orange and red.”
An AQI of 151200 is considered unhealthy, in the middle of the scale and coded in red. The 101150 range right below, coded orange, is unhealthy for sensitive groups. The highest range is 301500, considered hazardous, while good air quality ranges from 0 to 50 and moderate is 51100. The spike in readings is related to PM2.5, or fine particulate matter pollution, which is found in wildfire smoke.
AQI levels were worst in San Pablo, registering 191 late Tuesday morning, as well as 183 in Vallejo and 172 in Berkeley around the same time. Oakland’s AQI levels reached the high 160s, while the east part of San Francisco was seeing readings in the low 160s. Concord saw readings as high as 176 overnight, and midday Tuesday was in the 150s.
A Spare the Air Alert was previously set to run through Wednesday for the Bay Area, but on Tuesday it was extended to Friday. Wood burning is banned during alert periods.
The sheer number of wildfires burning all over the Bay Area and in nearby areas, combined with shifting wind patterns, means any area can be susceptible to unhealthy air quality.
“There’s the fires burning in Point Reyes and Sonoma County, and that smoke can be blown from the north down into the region,” Richardson said. “It’s a fluctuating situation now. The winds may be shifting now, and it’s a little bit hard to tell who gets affected the strongest.”
He said the district’s meteorologist is forecasting that sometime Wednesday or Thursday, the winds will shift to the more normal northwesterly flow.
In the meantime, Richardson encourages everyone to regularly check the air quality levels to help gauge how much time — if any — to spend outside.