Almost six years ago, the Chinese government adopted stringent policies to tackle the problem of particulate air pollution like limiting the number of cars on the roads and shutting down or replacing coal-fired power plants with natural gas. The efforts bore fruit and PM 2.5 concentrations in eastern China fell by almost 40%.
However, based on environmental data collected by over 1,000 air quality monitoring stations across the country, researchers from John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Nanjing University of Information Science & Technology (NUIST), found something surprising: While PM 2.5 pollution is falling, harmful ground-level ozone pollution is on the rise, especially in large cities.
As it turns out, when it comes to the war on air pollution, chemistry is a formidable foe. The researchers from SEAS and NUIST found that particulate matter acts like a sponge for the radicals needed to generate ozone pollution, sucking them up and preventing them from producing ozone.
But the rapid reduction of PM 2.5 dramatically altered the chemistry of the atmosphere, leaving more radicals available to produce ozone.