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Spare the Air Alerts and Air Quality Advisories are used to help inform residents about air quality in the Bay Area.
There are two primary pollutants of concern for the Bay Area: ozone, which is typically an issue during the warmer months, and fine particulate pollution, which is typically a concern during the wintertime, but can also be elevated year-round during wildfire events.
From April to October, warmer temperatures and longer days can cause ozone to build up to unhealthy levels. When this takes place, the Air District will issue a Spare the Air Alert for ozone.
On days when a Spare the Air Alert has been issued for ozone, Bay Area residents should consider limiting outdoor activities.
From November through February, the Air District will call a Spare the Air Alert when fine particle pollution is expected to build up to unhealthy levels. This usually takes place on cold, calm days when wood smoke from people's fireplaces and wood stoves gets trapped close to the ground.
A Spare the Air Alert for fine particle pollution can also be called outside the winter months, especially when there are wildfires impacting the Bay Area.
On days when a Spare the Air Alert is in effect due to high levels of fine particle pollution, it is illegal to burn wood, fire logs, pellets, or other solid fuels in fireplaces, wood stoves, outdoor fire pits, and other wood-burning devices.
There are everyday behavior changes, such as taking public transit, carpooling, or biking, that can improve air quality year round. These actions are particularly important on days when a Spare the Air Alert is called.
When local air quality is being affected by events such as wildfires, but federal health-based standards are not expected to be exceeded, the Air District will post an Air Quality Advisory.
For instance, an Air Quality Advisory might be issued when wildfire smoke is visible aloft in the atmosphere, but is not heavily impacting air quality at lower levels where people breathe.
If conditions during an Air Quality Advisory change, and pollution levels are expected to exceed federal air quality standards, a Spare the Air Alert will be called.
Air is almost always on the move. The nine-county Bay Area is a single air basin, and actions to cut back emissions in one part can have significant impacts on the air quality in locations miles away. That is why when air quality is expected to be unhealthy in any part of the Bay Area, a Spare the Air Alert is called for the entire region. Sign up for alerts.