Is the air you breathe very different from your neighbor’s? Probably not. But it might be pretty different from the air 20 miles away at the nearest state-run air monitoring station. Especially as wildfire season approaches, neighborhood-specific air quality measurements could let you know when to take precautions and when to breathe a sigh of relief.

Monterey Bay area residents are collecting their own air quality measurements and sharing them as part of a community wildfire monitoring network run by the Monterey Bay Air Resources District. This is one of the first jurisdictions in the country to set up such a network using these community-operated air sensors, according to Richard Stedman, the air pollution control officer at the District.

There are only six state and local air monitoring stations in the Monterey Bay Air Resources District, which is made up of the counties of Monterey, Santa Cruz and San Benito. “We thought that was good enough,” Stedman said. “It had been good enough for many, many years.”

But during the CZU lightning complex fires in 2020, those six stations left many people uncertain about the air quality where they were. For some residents, the nearest air sensor was 20 miles away or more.

But that’s starting to change. Over the past few years, personal air sensor equipment has become more accessible to community members. Individuals can purchase sensors and set them up at their homes. This lets them monitor the air right in their own backyard — literally — and then share it with their neighbors. The data from those sensors is available online from the Air District (www.mbard.org/wildfire-smoke-information-and-resources) or airnow.gov.

“It’s not as precise as somebody in a lab counting each particle,” Stedman said. “But they work fine for getting sort of a general idea of what’s in the atmosphere.”

And that information is incredibly useful not just for community members who want to keep track of their air quality but also for researchers.

“We’re seeing stuff that we never would have known in the past,” Stedman said. For example, if there’s a fire somewhere in Santa Cruz County, the sensor network lets the District track the smoke as it flows downhill to settle in Monterey. “We’re finding that there are areas throughout Monterey that smoke will concentrate in sort of like a lake because the smoke follows the ground contours.”

The air district publishes data from its six sensors as 24-hour average values. If air quality is bad in the morning and clears up toward the end of the day, it could take a while for the reported numbers to catch up. One reason for this is that the U.S. Environmental Protection Agency hasn’t set health standards for less than 24 hours of exposure to pollutants.

The community air quality monitoring network reports data more often, from more sensors and in more locations. “We’re getting data flow so people can sort of get an idea of what they’re experiencing,” Stedman said.

There are some drawbacks, however. The network relies on community members who might be following unscientific methods to take these measurements.

“I met this one woman who had a little solar panel on the back of her bike, and she would go chasing smoke,” Stedman said. “When she got there, she would deploy her little sensor and take a sample.” But the sensors are geo-tagged, so the air district was able to spot those spurious data points.

The more community members deploy sensors, the more useful and reliable the data will be. Residents who are interested in becoming part of the air quality monitoring network should visit the EPA’s Air Sensor Toolbox page (https://www.epa.gov/air-sensor-toolbox) for more information. More local information is available on the District’s Smoke Information and Resources page (https://www.mbard.org/wildfire-smoke-information-and-resources).

Residents of the Air District jurisdiction who can’t afford to purchase their own air quality monitoring system have options too. If a resident makes a compelling case that they could fill a hole in the air quality map, the Monterey Bay Air Resources District may be able to help them acquire a sensor.

Stedman said he’s happy this air monitoring network empowers communities to monitor their own air quality and protect their own health. “We’re really proud of this sensor network.”