New analysis from Smart Air shows that China is making progress on its “war on air pollution.” PM2.5 air pollution was down in 14 out of China’s 15 largest cities. Yet one region saw far more progress than the rest.
South Sees Modest Air Quality Gains
In southern China, from Shanghai to Shenzhen, air quality improved modestly. Shanghai saw air quality improve 9%.
This analysis uses over 21,000 daily average PM2.5 data points from official sensors around the country. These data points showed, for example, that Guangzhou’s PM2.5 fell a modest 3%.
Northeast Sees 2018 Air Quality Miracle
While most southern Chinese cities saw air quality improve by less than 10%, cities in China’s northeast improved by much more. Shenyang’s air quality improved by 19% in 2018.
Harbin saw the biggest improvement out of 15 major Chinese cities. Harbin’s air quality improved by an impressive 32%. With that improvement, Harbin moves from tied with Beijing in 2017 to 20% lower than Beijing in 2018.
Air Quality Measures Benefit North More Than South
This data suggests that China’s recent “war on air pollution” is having stronger effects in northern China than southern China. The switch from coal heating to natural gas naturally benefits the cold north more than the south. The more industrial northeast may also be benefitting more from the recent move to take diesel vehicles off the road.
Another factor is that northern China started from a worse baseline air quality. Even after the air quality progress, China’s five most polluted major cities are north of the Yangtze River. Thus, progress may be easier to produce.
Other northern cities saw large improvements in air quality too. Tianjin air quality improved 19%, while Xi’an improved 17%.
However, progress did not reach all of northern China. Zhengzhou actually saw PM2.5 go up 7% –the only one of these 15 cities to see air quality worsen in 2018.
Despite Progress, China’s Air is Still Harmful
Despite the northeastern miracle, its cities—and all 15major cities Smart Air analyzed—are far above the World Health Organization’s annual limit. Even China’s cleanest major city, Shenzhen, averages over twice the limit.
This limit matters because studies have shown that PM2.5 raises blood pressure, inflammation, and rates of heart attacks and strokes. This is true even at PM2.5 levels 50% below the lowest average in China.
Studies Document Protective Effects of Purifiers, Masks
Despite the harms of PM2.5, studies have found that wearing masks prevents harmful effects on blood pressure and heart rate variability. Similarly, placebo-controlled studies of air purifiers have found that reducing particulate in the home prevents harm to blood pressure, inflammation, and immune response—even among young, healthy twenty-year-olds.
Smart Air is a certified B Corp committed to combating the myths big companies use to artificially inflate the price of clean air. To help people living in polluted cities protect themselves, Smart Air provides empirically backed, no-nonsense purifiers and masks, thereby helping to lower the cost of clean air.
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Thomas is an Associate Professor of Behavior Science at the University of Chicago Booth School of Business and the founder of, a social enterprise to help people in China breathe clean air without shelling out thousands of dollars for expensive purifiers.