When the Wind Blows, Air Pollutants Travel across Chinese Cities

We use city-level data from the daily air pollution index and meteorological data on wind movement to see whether air pollution in China spills over from one city to another. We find that (i): a city’s average air pollution is expected to increase by 0.40-0.51 units (in the Air Pollution Index) if the average pollution in surrounding cities increases by one unit; (ii) an increase in gasoline price can improve air quality by discouraging driving; and (iii) high levels of precipitation and strong winds can mitigate air pollution, while the effects of temperature on air quality vary by time of day. Our findings suggest that pollution control policies must be coordinated among cities and provinces to effectively reduce urban air pollution, with the added benefit of reducing greenhouse gas emissions.