And you thought fireplace emissions were bad.

When smoke from the massive Ferguson Fire began pouring into the San Joaquin Valley last month, first it darkened the skies over Fresno, then it drifted south into Delano, Shafter and Bakersfield, turning the sunset an eerie amber-orange.

Bakersfield educator Tony Amarante didn't much like it. But he was armed with a tool most people don't have: a sensor attached to the eaves of his home that provides real-time measurements of dangerous PM 2.5 and other particle pollution common in wood smoke, diesel fumes and other pollutants.

"If we are concerned citizens and we can utilize available technology to monitor the air in our community and share that information with others," Amarante said, "that's my civic duty."

His isn't an isolated effort.

Amarante is part of a larger grassroots movement to provide, not just government agencies, but everyday people with the means to monitor air quality in their own neighborhoods. It is taking hold in Bakersfield and other areas in the San Joaquin Valley, maybe the most polluted region in the country.

All one needs is a couple hundred dollars for a PurpleAir sensor and a wi-fi connection, and your air readings become part of an online network.

"I want to know what the air quality is right outside my home," said Adrian Dybwad, the founder of PurpleAir who hails from South Africa but settled in the Salt Lake basin in Utah where he became concerned about emissions from a mining operation in his own backyard.

Dybwad and a small group of people with technical backgrounds came together to build an affordable air monitor. The PurpleAir website and map were started in November 2015. More than 2,000 monitors are now in place and the network is growing, Dybwad said.

Bakersfield resident Ann Gallon has one.

"The monitor is about the size of a coffee mug," Gallon said in an email. "It records particulate matter, PM 2.5, and gives a readout number representing AQI."

The PurpleAir map displays the results using the federal Environmental Protection Agency's AQI, or Air Quality Index scale. The AQI color scheme shows green for good air, yellow for moderate, and up the scale to orange, red and even purple, signifying 75 or more micrograms per cubic meter of air, a level designated "very unhealthy."

"An app on my smartphone lets me check my personal air anytime I wish, and the whole world can also check it by zeroing down on a world map from their computer to my Bakersfield neighborhood," Gallon said. "Just like Google Earth."

Gallon, like Amarante, has long been concerned about the valley's chronic air problem. As members of the Sierra Club, they believe multiple private sensors help provide an accuracy check on air monitors operated by the San Joaquin Valley Air Pollution Control District.

"It's not unlike having a semi-official weather station at your home or business," she said.

Indeed, more monitors helps provide more credibility in the readings. When multiple sensors in a single area are in the same ballpark in their measurements, it suggests a level of accuracy.

Sharing the data and research with others created a need for more monitors to expand the network and to test the sensors by grouping them with other monitors, Dybwad said.

The monitors use laser beams to detect particles going past by their reflectivity, like dust shimmering in a sunbeam. The PM 2.5 and PM 10 micro-gram weights are calculated from the counts. The values are averaged every 20 seconds and graphically displayed on the website.

Sayed Sadredin, the longtime director of the air district who retired last month, said he understands why residents in pollution-impacted neighborhoods and communities would want to be able to monitor their own air quality.

But the PurpleAir monitors, he said, are less accurate, especially as they get older. And they cannot be depended on as tools to influence public policy.

That's fine, advocates say. No one expects the cheaper monitors to be the sources of official air quality readings.

But they help fill gaps. For example, Bakersfield, a sprawling city that stretches for miles in every direction, has just one "official" PM 2.5 monitor near California Avenue.

What about Oildale, advocates ask. What about northeast Bakersfield? Rosedale? Greenfield? Lamont? Arvin? Delano? Wasco?

Gallon worries the air district is "long on plans and short on aggressive teeth to improve our air."

The monitors, she said, empower the public. They're not a silver bullet, but they are another tool regular people can use to light a fire under bureaucrats.

PurpleAir's founder said it's just as important to look for good air as bad.

"It's just as useful," he said. "That's when you can let your kids go outside to play."

Steven Mayer can be reached at 661-395-7353. Follow him on Facebook and on Twitter: @semayerTBC.

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