Nitrogen dioxide levels before (left) and after (right) stay-at-home orders went into effect in early 2020. Darker colors indicate more pollution. UC San Diego School of Global Policy and Strategy
The near-halt in traffic resulting from California’s 2020 stay-at-home orders revealed the outsized role that cars and trucks have in polluting Hispanic and Asian communities, according to a new study.
“People who live in communities where highways are built right through them are breathing other people’s transportation emissions,” said Luke Sanford, assistant professor at the Yale School of the Environment and co-author of the study. “The Covid shutdown was like a big switch that turned off 90 percent of transportation.”
In California, communities of color tend to see higher levels of pollution than white communities, but it can be hard to discern the sources of the pollution. The state’s Covid-19 stay-at-home orders offered some insight.
Comparing levels of particulate matter and nitrogen dioxide before and after the shutdown, researchers found that pollution fell in Asian and Hispanic communities more than it did in white communities. The results suggest that traffic is to blame for poorer air quality in Asian and Hispanic neighborhoods. Income only explained 15 percent of the disparity.
The shutdown also cut pollution in Black communities, but it did not narrow the gap between Black and white neighborhoods, indicating that power plants or other sources of pollution are to blame for differences in air quality. The findings were published in the journal Nature Sustainability.
“One would think that in a state with strong environmental policies, where we track what is being emitted where, that our regulatory system might do a good job of protecting everyone equally,” said Jennifer Burney, an environmental scientist at the University of California, San Diego and co-author of the study. “But this is really strong evidence of systemic bias. Pollution sources from everything that was shut down, transportation, businesses, restaurants, etc. all add up during business-as-usual conditions. Thus, the total system is tipped, exposing racial and ethnic minorities to more pollution.”
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