Student Studies Progress After Chinese ‘Airpocalypse’

Posted on: July 13, 2017 Topics: air pollutants, air pollution, student

Chloe Kim in China headshotFor her first couple of days in Beijing, environmental health doctoral student Chloe Kim had trouble breathing. “I could feel in my throat how bad the air was,” she says. After a week she says she got used to it—but knows the air she’s breathing is far from healthy.

Through a National Science Foundation fellowship, Kim is spending the summer at Tsinghua University in Beijing to evaluate the health impact of China’s 2013 Air Pollution Prevention and Control Action Plan.

The Chinese government announced the Air Pollution Prevention Plan following a period of off-the-charts air pollution in early 2013, which affected half a billion people in northern China, closed roads and schools, and forced tens of millions to stay indoors for days. Known as the ‘airpocalypse,’ it spurred the Chinese government into action with a plan targeting multiple sectors in the country to reduce air pollution.

Kim’s project is focusing on one of the country’s most populous—and polluted—regions, the neighboring cities of Beijing and Tianjin and the surrounding province of Heibei. She is also focusing on one kind of air pollutant, atmospheric particulate matter under two and a half micrometers in diameter—PM2.5.

“PM2.5 is small enough to penetrate into the human respiratory system and can reach the deepest regions of the lungs,” Kim says. “There is an array of health effects associated with PM2.5, including premature death from cardiovascular or respiratory diseases, aggravation of asthma, decreased lung function, nonfatal heart attacks, and difficulty breathing.”

Kim is using simulated PM2.5 emission estimates from three different air pollution reduction scenarios calculated by her colleagues at Tsinghua University, along with population and epidemiological data, to calculate the action plan’s health impact in the region.

That calculation involves finding the right CRF—concentration-response function—to accurately characterize the association between PM2.5 and health outcomes, Kim says, because using a CRF derived from previous cohort studies in Western countries might not accurately represent the true exposure-disease association in China.

Kim is the only person working on this project, and she says she is grateful for the knowledge she brings from SPH, “like where to find necessary data, how to evaluate the accuracy of data, and being able to understand different methodologies used in different research studies. Having an overall understanding of the project and being able to answer questions along the way is also very important.”

She is also learning plenty, she says, both technically and interpersonally. “Part of the reason why I wanted to study air pollution for my PhD degree was China’s air pollution problem,” she says. “I really wanted to directly talk to and hear from people about their opinions about air pollution and their experiences living here.”

The air quality app Air Visual

The air quality app Air Visual

What is most striking, Kim says, is how people can get used to air pollution—including her. “People that live here got used to the environment a long time ago,” she says, and she often hears Beijing residents call everyday but unhealthy air quality “good.”

Since arriving in Beijing, Kim has been using a color-coded air pollution monitoring phone app: green is good, yellow is moderate, orange is unhealthy for sensitive groups, red is unhealthy, purple is very unhealthy, and brown is hazardous. “I have never seen a green day since I got here on June 8,” she says. “It’s normally red, and sometimes yellow or orange—but I’ve only had two or three purple days and no brown days, so it can be considered ‘better’ to people who are used to seeing worse air days.”

To illustrate, she says, PM2.5 levels on July 11 were four times higher in Beijing than in Boston, and in Beijing that qualified as a “good, yellow day.” She still feels it in her throat when the air quality hits purple, but on orange and red days Kim says she now feels fine. She is even biking everywhere, and swears by Beijing’s bike-sharing system. It’s cheap and extensive, she says—and has zero emissions.

Michelle Samuels

Chloe Kim is taking over the SPH Instagram account from July 17 through 21 to share photos from Beijing. Follow along at

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