A highway winding through Los Angeles

Pandemic Shutdowns Give Window into Environmental Racism in California’s Air Pollution Policy

Study finds that though air pollution is highly regulated in California, environmental policy as a whole is not protecting all communities in an equal way: Regulatory machinery has been preferentially protecting White, non-Hispanic people from exposure.

In the midst of the COVID pandemic when stay-at-home orders were given in California, a team of interdisciplinary researchers, including Yale School of the Environment Assistant Professor of Environmental Policy and Governance Luke Sanford, started discussing an idea. Observing the quiet on the roads, they asked: How does the lockdown and reduction in pollution from sources such as transportation affect different communities? And can this sudden change help them figure out why low income and non-white communities have such worse air quality?

“Part of the problem from a policymaker's perspective is that they don't know what the sources are of pollution disparity. We don't know if it's from power generation or from businesses, if it's from highways, roads, or if it’s from agricultural production, which has a big air pollution impact in California,” says Sanford. “The COVID shutdown was like a big switch that turned off 90% of transportation.”

The state’s shutdown orders, which went into effect in March 2020, were among the most restrictive in the country, enabling the researchers of the study to demonstrate that the disparate impacts cannot be explained by weather patterns, geography, income, or local economic activity.

“After we'd accounted for all these other things which we know caused disparate pollution impacts, the facts were that Hispanic, Latinx, and Asian people had higher exposure to pollution from transportation,” Sanford says.

The team’s analysis, published in the journal Nature Sustainability, showed that even though air pollution is highly regulated in California, environmental policy as a whole is not protecting all communities in an equal way — sheltering in place produced disproportionate air pollution reductions for Hispanics and Asians, as well as in  low-income communities. They  are disproportionately affected by pollution coming from the in-person economy, which includes activities such as going shopping, to restaurants or bars, and to work.

There is this legacy of structural, institutional racism that persists and is really damaging to the health of many of California's residents.”

Luke SanfordAssistant Professor of Environmental Policy and Governance

“There is this legacy of structural, institutional racism that persists and is really damaging to the health of many of California's residents,” Sanford says.

The surprising finding was that income wasn’t the main driver of the disparate impacts.

Map showing NO2 levels in California before and during COVID-19
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Air Pollution Distribution Inequities

Explore the study’s air pollution and census data on air pollution distribution inequities.

“Income only explains about 15% of the disproportionate decrease in air pollution experienced by Asian and Hispanic communities during the shutdown,” says co-author Jennifer Burney, the Marshall Saunders Chancellor’s Endowed Chair in Global Climate Policy and Research at the School of Global Policy and Strategy at the University of California, San Diego. “This may be surprising to many because people tend to conflate income and race, both because systemic discrimination is a hard thing to face and because we have accepted that we live in a world where individuals can ‘buy’ cleaner air through higher housing prices in less polluted areas.”

The study relied on satellite records of nitrogen dioxide and ground-based monitoring networks for respirable particulate matter and used daily and weekly pollution observations — along with demographic, geographic, and mobility data — to estimate how much race and ethnicity alone explain the changes in air pollution exposures experienced during the shutdown. The research team built a computer model to predict pollution levels stemming from temperature, precipitation, and relative humidity, which are the key atmospheric conditions that determine pollution levels.

Study co-author Pascal Polonik, a PhD candidate at the Scripps Institute of Oceanography, noted the importance of the pollution sensors to gather data in impacted communities and access to the information.

“Communities need to be engaged in meaningful ways to ensure that everyone has access to what should be a democratic process. Data from crowdsourced sensors like the ones that were used in this study can improve access to information and could help communities be part of informed decision-making. Unfortunately, these sensors tend to be located in the places least likely to be impacted by unjust pollution exposure,” he says.

One key takeaway from the data analysis, the authors note, is that policies that impact transportation emissions could have important environmental justice impacts for California’s Asian and Hispanic communities. Communities built closer to highways, for example, are more highly impacted by transportation pollution. 

"People who live in communities where highways are built right through them are breathing other people’s transportation emissions," Sanford says.

The authors note that the study shows there is no standard or test for making sure that new or existing sources of air pollution do not perpetuate environmental injustice. The study, they say, suggests that such a test, combined with increasing availability of air quality data and community input, may point the way to a more just future for all.


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