As powerful downslope winds sent the deadly Camp Fire raging through bone-dry vegetation in northern California on November 8, 2018, sensors on the ground and in space began to detect sharp increases in air pollution downwind of the inferno.
From space, the Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) sensor observed expansive smoke and aerosol plumes over California’s Central Valley and coast soon after the fire began. Likewise, the Ozone Mapping Profiler Suite (OMPS) on Suomi NPP observed unusually high aerosol levels, and the Measurement of Pollution in the Troposphere (MOPITT) on Terra picked up strong carbon monoxide signals from the fire.
Meanwhile on the ground, atmospheric scientists Pawan Gupta, Robert Levy, Prakash Doraiswamy, and Olga Pikelnaya have been keeping a close eye on air quality data from a network of low-cost sensors distributed throughout the region. These sensors measure the mass concentration of fine particulate matter (PM2.5). Some stations measured PM2.5 values higher than 500 micrograms per cubic meter, which is about 40 times higher than the level considered safe to breathe.
#fires and #smoke in CA continue deteriorating air quality in the region – satellite images from @NASA_NPP #VIIRS #OMPS and low-cost sensor network @purpleairq shows hazardous conditions @NASA_HAQAST @NASAEarthData @iccialtopenburn @Open_AQ @R5_Fire_News @USRAedu @SanGasso pic.twitter.com/lhO08wUg4i
— Pawan Gupta (@pawanpgupta) November 11, 2018
“On November 9th, due to favorable wind direction, most of the smoke was confined to a smaller region north of San Francisco, but the wind direction changed on the 10th, and smoke spread over a much larger region,” noted Gupta, who is based at NASA’s Marshall Space Flight Center and works with NASA’s SERVIR and ARSET programs. “On the 11th and 12th, the wind direction again changed, and most of the smoke blew over the ocean.”
Gupta is involved in an ongoing effort to deploy and test low-cost commercial air quality sensors to see how well their measurements compare with standard EPA measurements and NASA satellite observations. The ground-based sensors that are part of official state and federal government observing networks cost several thousand dollars each, but the new generation of sensors cost just a few hundred dollars—cheap enough that Gupta thinks they could proliferate and potentially be used to help fill in crucial gaps, particularly in countries with few air quality sensors.
“The low-cost sensors have performed as expected, though with varying accuracy for certain types of particles,” said Gupta. “Going forward, we hope to use what we learn from them to improve the techniques scientists use to derive levels of particulate matter at the surface from the entire column aerosol measurements observed by satellites.”
So far, Gupta and his colleagues have deployed about 40 low-cost sensors in California. Next summer, they plan to add hundreds of additional sensors in New Delhi, an area that regularly gets hit with dust storms and smoke from agricultural burning. They also plan to deploy sensors in North Carolina, an area with relatively clean air.
Citizen scientists interested in air quality can get involved in the project. Gupta and colleagues from RTI International, South Coast Air Quality Management District, NASA, and other institutions are recruiting volunteers to host the low-cost sensor and share the results with the experts.
Air Quality Citizen Science, Project Goals and Overview
EOS, New Strategies to Protect People from Smoke During Wildfires
KVPR, NASA’s JPL Using Fresno As A Test Bed For Air Quality Research
Geohealth, Impact of California Fires on Local and Regional Air Quality: The Role of a Low‐Cost Sensor Network and Satellite Observations