Sonoma County residents turning to their own air quality monitors since Camp fire

When the Camp fire in Butte County blanketed Sonoma County and the greater Bay Area with hazardous smoke for two weeks, shutting down schools and forcing most activities to shift indoors, people across the region turned to an unofficial online map to track air quality.

Populated with hyperlocal data from pollution sensors installed by residents or organizations, PurpleAir.com became an indispensable resource for people wanting information about the smog obscuring blue skies. Sonoma County school officials even tapped the site to decide whether the air was too toxic to hold class.

The number of local data points increased over the last several weeks as people - hungry for data to confirm what their eyes saw - realized there weren’t sensors in their neighborhoods. They included Cotati resident Sandra Knoy, who decided to buy a $230 PurpleAir monitor and join the network.

With asthma and two young children, Knoy said she wasn’t satisfied that readings in Santa Rosa and Sebastopol reflected what the air was like in her city.

“It’s nice to have something more local - my kids go to school one mile away, we go to parks downtown within walking distance,” Knoy said. “I thought, we can do this, ‘It’s citizen science.’?”

Knoy said she and her children, ages 7 and 10, have been tracking data from their backyard sensor - a device slightly bigger than a softball that uses a laser to count particles in the air - every day since they installed it Nov. 16.

The Wi-Fi-connected device sends data to the cloud and places a color-coded dot on the map with a numerical reading based on the Environmental Protection Agency’s Air Quality Index. Knoy’s family has watched their dot shift from deep red - indicating hazardous air - down the scale from orange to yellow to green - or good air quality.

This week’s storm brought wind, rain and relief to the area, but this newly built network of citizen air quality data points remains and will be in place for the next air quality disaster.

“We’re in a new era of personal air quality monitors,” said Rob Bamford, air pollution control officer with the Northern Sonoma County Air Pollution Control District.

The district, which encompasses much of western and northern Sonoma County, has a high-tech, federally certified air quality monitor on Morris Street in Sebastopol. Those readings are considered more accurate than those on PurpleAir. However, there’s just one for an entire district serving ?50,000 people, and the monitors costs about $75,000 each, requiring maintenance and expertise, he said.

A California law passed last year created new requirements for community-based air quality monitoring programs. Bamford said the pollution district received the sensors at no cost through the California Air Resources Board.

Bamford’s district and others are experimenting with building more robust networks of air quality reports using inexpensive sensors like the kind made by PurpleAir. This summer the district installed a PurpleAir outside the district’s Healdsburg office. Once the Camp fire ignited, they installed six more.

“You zip tie it or hang it on a hook, and if you have WiFi you hook it up and away you go,” Bamford said about the monitors.

However, he said PurpleAir sensors appear to show slightly more elevated pollution levels compared to official monitors, something he hopes people and organizations take into account when using the resource.

“People should focus on the change (in air quality) over time and the movement but realize the numbers skew high,” Bamford said.

Adrian Dybwad, founder of PurpleAir, said he’s aware the numbers can skew high compared to government monitors because of the technology used “but not significantly higher to make the readings meaningless.”

“If it says ‘very very bad,’ it’s still bad, it’s still harmful,” Dybwad said.

Dybwad, who has a background in electronics and computer programming, first got the idea to develop an inexpensive air quality monitor because he was concerned about pollution from a nearby gravel pit near his home south of Salt Lake City.

He started selling the devices in 2016, and there are currently over ?3,000 sensors contributing air quality data to the online map. Dybwad said his goal is to provide people with an inexpensive tool to address air quality concerns in their communities.

The site provides a unique way to compare air quality across the globe. In the U.S. states vary in how they record and report air quality. Other countries also have different standards for measuring pollution.

But a PurpleAir monitor in Hong Kong is using the same standard as one in Santa Rosa.

That provided startling comparisons last week when Sonoma County’s air quality hit levels of chronically polluted cities such as New Delhi and Beijing.

Dybwad said he’s planning to improve the data presentation on his website and may try to reflect the different types of air pollution that exist in different regions.

“It’s just as important to know where the good air is as it is to know where the bad air is,” Dybwad said.

Sonoma County still has air quality “sensor deserts,” particularly on the westside. Sonoma County Supervisor Lynda Hopkins said she’s considering putting one up at her Forestville property because few sensors exist in her area.

Sonoma Valley Hospital officials installed two sensors, one inside the emergency room admittance area and another outside, to help them make day-to-day decisions when the air quality was at its worst.

Hospital spokeswoman Celia Kruse de la Rosa said they ultimately rely on official government air quality reports, but they also wanted to track the air outside their buildings and participate in community-generated local air quality data.

“It helps citizens in the valley to have a reading that is actually in the valley,” Kruse de la Rosa said. “Our conditions are going to be different from those in Santa Rosa and those in Napa.”

You can reach Staff Writer Julie Johnson at 707-521-5220 or julie.johnson@pressdemocrat.com. On Twitter @jjpressdem.