Whites Contribute More to Air Pollution – Minorities Carry Burden: Gunshots

Pollution, just like wealth, is not distributed equally in the United States.

Scientists and policy makers have long known that black and Hispanic Americans tend to live in more polluted neighborhoods than white Americans. And since exposure to pollution can cause a range of health problems, this inequality could be a source of unequal health outcomes in the United States.

A study published Monday in the journal PNAS adds a new twist to the problem of pollution by looking at consumption. While we tend to think that factories or power plants are a source of pollution, these polluters would not exist without consumer demand for their products.

The researchers found that air pollution is disproportionately caused by the consumption of goods and services by white Americans, but that it is inhaled disproportionately by black and Hispanic Americans.

"This article is exciting and really quite innovative," says Anjum Hajat, an epidemiologist at the University of Washington, who did not participate in the study. "The inequality of exposure to air pollution is well documented, but this study introduces the angle of consumption."

Hajat says the study reveals an inherent injustice: "If you contribute less to the problem, why should you suffer more?"

The study, led by engineering professor Jason Hill at the University of Minnesota, lasted more than six years. According to Christopher Tessum, the journal's first author, a postdoctoral researcher at the University of Washington, the idea arose from a question asked at a conference.

Tessum presented previous research on how blacks and Hispanics are often more exposed to air pollutants than whites. Once he has finished, someone asked "if it would be possible to tie the exposure to air pollution to the person who consumes," he said. Tessum. According to Tessum, no one has ever tried to answer this question.

It is a complex and complex problem, but its study could answer a fundamental question: do those who pollute, through their consumption of goods and services, share the costs equitably?

What kind of data could even answer such a complex question? Let's break down:

Researchers would need to know how polluted the air was, what communities were exposed to the pollution and what the health effects would be.

Then, for the same area, researchers should identify the sources of this exposure (coal-fired plants, factories, agriculture to name a few) and get an idea of ​​the goods and services that come from these emissions ( electricity, transport, food). .

Finally, who consumes goods and services in these sectors of the economy?

"The different types of data, in themselves, are not that complicated," says Tessum. "It connects them where things get a little harder."

The most relevant measure of air pollutants for human health is "particulate matter 2.5" or PM2.5. It is the largest risk factor for environmental health in the United States, with higher levels associated with more cardiovascular problems, respiratory diseases, diabetes and even birth defects. PM2.5 pollution is mainly caused by human activities, such as fossil fuel combustion or agriculture.

The EPA collects this data through the National Emissions Inventory, which includes emissions from specific emitters, such as coal-fired power plants or factories, measurements of mobile polluters such as cars or airplanes, and events. such as forest fires, thus providing a comprehensive picture of pollution in the United States.

The researchers generated maps showing where different transmitters, such as agriculture or construction, were at the origin of P2.5 pollution. Coal-fired plants generated pockets of pollution in West Virginia and Pennsylvania, while agricultural emissions were concentrated in the Midwest and Central Valley of California. "We then linked the census data to understand where different ethnic and racial groups lived to understand exposure patterns," said Hill.

Tessum then used previous research on the health effects of different levels of exposure to estimate the number of premature deaths per year (out of a total estimated at 102 000 human-caused emissions) which can be linked to each issuer.

"We wanted to go further in this study by assigning responsibility for these premature deaths to different sectors. [of the economy]and ultimately to consumers, and perhaps to consumers of different racial and ethnic groups, "Hill said.

To do this, researchers have in fact worked backwards, following consumer spending in different sectors of the economy, and ultimately in the main emitters of air pollution.

Take one of the main contributors to emissions: agriculture. The Bureau of Labor Statistics' consumer spending surveys provide detailed data on the amount of household spending in various sectors of the economy, including food.

These data gave researchers an idea of ​​the amount of food spent each year by blacks, Hispanics and whites. Other expenses, such as energy or hobbies, are also measured. Taken together, these data represent the consumption patterns of the three groups.

To translate dollars spent on food into levels of air pollution, researchers traced money back through the economy. Using data from the Bureau of Economic Analysis, researchers can estimate, for example, the amount of food spent by grocery stores or restaurants. In the end, these dollars are tied to the major emitters – farms producing food or fuel that farmers buy to run their tractors.

Researchers have now completed the chain of causation, ranging from dollars spent on groceries to the amount of pollution emitted into the atmosphere. By completing this chain for each source of pollution, it was revealed that its consumption was causing air pollution and was suffering from it.

After taking into account the differences in population size, whites suffer about 17% less air pollution than they produce due to consumption, while blacks and Hispanics are respectively 56 % and 63% more pollutants than their consumption, according to the study.

"These patterns did not seem to be motivated by different types of consumption," says Tessum, "but by different overall levels." In other words, whites consumed disproportionately more identical goods and services, generating air pollution, than minority communities.

"These results, as striking as they are, are not really surprising," says Ana Diez Roux, an epidemiologist at Drexel University, who did not participate in the study. "But it's really interesting to see the consumption habits documented in a rigorous way suggesting that minority communities are exposed to pollution for which they bear less responsibility."

Diez Roux thinks it's a good first step. "They have certainly made assumptions in their analysis that could be questioned in the future, but I doubt that the general trend that they have found will change," she says.

Tessum highlights some encouraging results from the study. Exposure to PM2.5 from all groups decreased by about 50% between 2002 and 2015, in part because of regulation and displacement of the population away from polluted areas. But the inequality remains essentially unchanged.

While further research is needed to fully understand these differences, the results of this study raise questions about how to address these inequities.

Tessum points out that "we are not saying that we should take money out of whites, or that people should not be able to spend money". He suggests continuing to strive to make economic activity and consumption less polluting could be a way to manage and reduce inequality.

Diez Roux thinks that stronger measures may be needed.

"If we want to reduce this inequality, we may have to rethink the way we build and build our cities, our dependence on car transport," said Diez Roux. "These are difficult things that we have to consider."

Jonathan Lambert is an intern at NPR's Science Desk. You can follow him on Twitter: @evolambert