Analyzing new air quality data, Smart Air found that Beijing’s PM2.5 dropped 14% in 2018 compared to the year before. Despite the improvement, Beijing still averages nearly five times the World Health Organization’s annual limit.
Improvement Came Mostly from Winter Enforcement
By breaking down the data month by month, analysis shows that the air quality improvement came mostly during the winter period. The rest of the months saw relatively similar levels to 2017.
Much of this improvement is likely due to the switch from coal heating to natural gas. Following the switch in late 2017, winter air quality improved noticeably.
This progress in air quality comes on top of progress the year before. Year 2017 was already Beijing’s cleanest on record.
Despite Progress, Beijing Still Among China’s Dirtiest Cities
Although its air quality has improved, Beijing is not one of China’s cities with the cleanest air. Among 15 of China’s largest cities, Beijing is in fourth place as of 2018.
Beijing air quality also lags far behind major developed cities internationally.
More Air Quality Data Becomes Available
Chinese cities now have more PM2.5 data than ever before. Before the US Embassy started publishing PM2.5 data in 2008, public data was unavailable.
However, new data has limits. For example, journalists uncovered officials spraying water near a sensor in an attempt to lower the numbers.
This data covers PM2.5 pollution, particles smaller than 2.5 microns in diameter that can penetrate deep into the lungs. Particles this small can even enter the bloodstream. Studies have shown that PM2.5 raises blood pressure, inflammation, and rates of heart attacks and strokes.
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.
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.