In the midst of the COVID pandemic, as California was being grounded, a team of interdisciplinary researchers, including assistant professor of environmental policy and governance at Yale School of the Environment Luke Sanford, began discussing an idea. As they watched the silence on the streets, they asked: How is closing down and reducing pollution from sources like traffic affecting different communities? And can this sudden change help them figure out why low-income and non-white communities have such poor air quality?
“Part of the problem from the perspective of policymakers is that they don’t know what causes pollution inequality. We don’t know if it’s from power generation or from businesses, from highways, roads, or from agricultural production, which has major air pollution impacts in California,” Sanford said. “The COVID shutdown was like a big switch that shut off 90% of traffic.”
The state shutdown orders that went into effect in March 2020 were among the most restrictive in the country, allowing the study’s researchers to show that the varying impacts cannot be explained by weather patterns, geography, income, or local economic activity.
“After we factored in all these other things that we know have different impacts on pollution, the facts were that Hispanics, Hispanics, and Asians were exposed to more pollution from transportation,” says Sanford.
The team’s analysis, published in the journal nature sustainability, showed that although air pollution is highly regulated in California, overall environmental policies do not protect all communities equally—protection at the spot resulted in disproportionate reductions in air pollution for Hispanics, Asians, and in low-income communities. They are disproportionately affected by pollution from the personal economy, which includes activities such as shopping, going to restaurants or bars, and going to work.
“There’s this legacy of structural, institutional racism that lingers that is really damaging to the health of many California residents,” Sanford said.
The surprising result was that income was not the main reason for the differential impact.
“Income explains only about 15% of the disproportionate drop in air pollution that Asian and Hispanic communities have experienced during the shutdown,” said co-author Jennifer Burney, the Marshall Saunders Chancellor 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 come as a surprise to many because people tend to confuse income and race, both because systemic discrimination is hard to tolerate and because we have accepted that we live in a world where individuals are challenged by higher property prices Less polluted areas can ‘buy’ cleaner air.”
The study drew on satellite recordings of nitrogen dioxide and ground-based respirable particulate matter monitoring networks, 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 levels during the shutdown. The research team created a computer model to predict pollution levels given temperature, precipitation and relative humidity, the key atmospheric conditions that determine pollution levels.
Study co-author Pascal Polonik, a graduate student at the Scripps Institute of Oceanography, pointed out the importance of the pollution sensors to collect data in affected communities and access the information.
“Communities need to engage in meaningful ways to ensure everyone has access to what should be a democratic process. Data from crowdsourced sensors like those used in this study can improve access to information and help communities be part of informed decision-making. Unfortunately, these sensors tend to be in the places least affected by unwarranted pollution,” he says.
A key finding from the data analysis, the authors say, is that policies that affect transportation emissions could have important environmental justice implications for California’s Asian and Hispanic communities. For example, communities built closer to freeways are more affected by traffic pollution.
“People who live in communities where highways are being built right through them are breathing in other people’s traffic emissions,” says Sanford.
The authors note that the study shows that there is no standard or test to ensure 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, could point the way to a fairer future for all.