(Illustration by Adam McCauley)
What happens when people in countries where the government offers little pollution monitoring learn that the air quality is dangerous? A new study details how the US Embassy in Beijing began to monitor the Chinese capital’s air-pollution levels and tweet about them in 2008. The program later extended to other US embassies in cities around the world. The practice led to a measurable decline in air pollution in those cities, few of which had local pollution monitoring before, the researchers found.
The paper’s authors, Akshaya Jha, an assistant professor of economics and public policy at Carnegie Mellon University, and Andrea La Nauze, a lecturer at the School of Economics at the University of Queensland, used satellite data to compare pollution levels, measured annually. The researchers found that the level of air pollution went down after the local US embassy began tweeting pollution numbers from monitoring equipment that diplomatic personnel had installed.
The embassy program yielded a drop in fine-particulate concentration levels of 2 to 4 micrograms per square meter, leading to a decline in premature mortality worth $127 million for the median city in 2019. “Our findings point to the substantial benefits of improving the availability and salience of air-quality information in low- and middle-income countries,” Jha and La Nauze write.
News coverage of the US government’s Beijing pollution monitoring sparked the researchers’ interest, La Nauze says. At the time, American diplomats were quoted saying that the embassy’s tweets led to marked changes in pollution levels in Beijing. When the researchers learned that the US State Department had extended the program to embassies around the world, they thought there might be a way to evaluate the diplomats’ claims empirically.
A problem the researchers confronted was how to quantify the impact of measuring something that had never been measured before. “The innovation of using satellite data meant we could go back and use historical satellite data to measure pollution before it was even being measured locally,” La Nauze says.
Jha and La Nauze also looked at the changes in US State Department employees in a given city receiving hardship pay over time, finding that it fell consistent with the pollution data. This was another indicator that the pollution counts, which would have triggered hardship pay for diplomats at certain levels, were falling. Local residents were also taking notice, with Google searches for related terms like “air quality” rising after a nearby embassy began tweeting, the researchers found.
Why would the embassy’s tweets make a difference? “The daily reporting of PM2.5 readings from embassy monitors may arm local and federal governments with the evidence necessary to implement pollution policy in host cities,” the researchers write. A combination of factors could also contribute to the lowering of pollution levels, La Nauze says, including implicit pressure from the US government that spurred local authorities to make policy changes, advocacy from local residents, or individuals changing their behavior. Local residents might also trust this new data because they feel the US government, as a third party, has no reason to manipulate the readings.
The paper will inform arguments over how to ameliorate air pollution, La Nauze says. The World Health Organization has argued for more monitoring, but without evidence that monitoring helps. “Our paper shows that information is a really key part of that tool kit,” she says. “Monitoring programs could be extremely good value for money in this fight.”
While a large part of the literature reveals that air quality matters to human health, few studies have shown how to solve air-pollution problems in specific locations, says Marshall Burke, an associate professor in the department of Earth System Science at Stanford University.
“This paper is a wonderful example of the latter, showing that the provision of information about air quality in low- and middle-income countries (where this information is typically very hard to come by) can alone lead to improvements in air quality, presumably because raising awareness of poor air quality induced local officials to do something about it,” he says.
The embassy program also helped the US government, he notes.
“The authors even go further and show that even for the US State Department alone, the installations of the monitors at embassies was cost-effective, since by improving air quality it lowered the hardship pay it had to pay diplomats—so the monitors easily paid for themselves,” Burke says.
Akshaya Jha and Andrea La Nauze, “US Embassy Air-Quality Tweets Led to Global Health Benefits,” Proceedings of the National Academy of Sciences, vol. 119, no. 44, 2022.
Read more stories by Chana R. Schoenberger.