With millions of people sheltering in place across the San Francisco Bay Area, the daily ebb and flow of urban life has come to a sudden halt.
The COVID-19 pandemic has upended many patterns and placed tremendous strain on medical, economic, political and social systems. The corresponding drop in regional traffic, along with reduced industrial and commercial activity, also has led to a significant decline in air-polluting emissions. While images of empty freeways paint a surreal picture, they also give us an unprecedented glimpse into what happens to the air we breathe when we drastically and suddenly cut emissions.
This was certainly the case in China. Satellite images released by NASA and the European Space Agency that many have seen showed a significant reduction in nitrogen dioxide (NO2) in China from January to February.
While satellite-based measurements give us a bird’s eye view of pollution over a region, ground-based measurements help us understand the pollution people are experiencing at the street level. To see how Bay Area air quality is being affected by efforts to flatten the curve of COVID-19, we are analyzing data from Aclima’s hyperlocal network deployed across all nine Bay Area counties, along with complimentary air quality data sources. We start with a simple question: To what degree have air pollution levels changed in the Bay Area over the past two weeks? Over the next several weeks, we will continue to release insights and findings from our ongoing analysis.
Comparing current Bay Area air pollutant levels to years past
To better understand the impacts of our collective responses to COVID-19 on Bay Area air pollution, we took a closer look at NO2, fine particulate matter (PM2.5), ozone (O3), carbon monoxide (CO) and black carbon (BC) in the Bay Area as reported by the Air Quality and Meteorological Information System (AQMIS) for weekdays from March 9 to March 20, and compared them with the average AQMIS-reported weekday levels for the same time period from 2017, 2018 and 2019. (…)
Melissa Lunden and Meghan Thurlow
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