SAN FRANCISCO (KPIX 5) – That wasn’t a filter over the San Francisco Bay today, that was particulate matter clogging the skyline.

“It’s very bad and troubling since there are no forest fires – you can barely see past Treasure Island,” said Kim Blake, who was visiting from Phoenix.

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The AQI across the Bay Area soared above 150 at times. Check your current air quality here.

The Bay Area Air Quality Management District said a temperature inversion – in which cooler air is nearer to earth’s surface with a layer of warmer air above – is trapping all the particulate matter.

The air district said that while vehicle emissions contribute to air pollution, it is primarily driven by wood smoke pollution, which is the largest source of PM2.5 in the Bay Area during the winter.

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A Spare the Air alert wasn’t issued, however, as the district said the air quality improved during the day.

“We are not expecting federal air quality standards to be exceeded – those are averaged over a 24 hour period,” said Aaron Richardson, spokesperson for the BAAQMD.

If you have asthma or fall into sensitive categories, you might want to think about ditching your outdoor exercise for a few days.

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