Guojun He, Yuhang Pan, and Takanao Tanaka; Nature Sustainability 

Key Takeaways:

  1. Overall, the Air Quality Index (AQI) improved by 22 percent and particulate pollution (PM2.5) improved by 24 percent.
  2. Compared to cities without formal lockdown policies, locked down cities saw their AQI and particulate pollution levels both
    decline by 17 percent.
  3. Compared to the previous year, cities not locked down saw a 7 percent decrease in particulate pollution and a 5 percent decrease in the AQI, suggesting that the disease preventive measures matter for air quality in cities even without formal lockdown.
  4. The effects of the lockdowns on air pollution were greater in cities with a larger economy, greater industrial activities and traffic, and
    higher demand for coal heating.
  5. Even with significant restrictions on daily life and commerce, pollution levels in China were still four times greater than what the World Health Organization considers safe. The study confirms that traffic, industrial and coal heating systems are important sources of air pollution and highlights the necessity to better control emissions from these sources moving forward.