Does lockdown reduce air pollution? Evidence from 44 cities in northern China

Area of Science:

• Environmental Science
• Public Health
• Epidemiology

Background:

• The COVID-19 pandemic prompted unprecedented quarantine measures in China.
• Significant reductions in human mobility, production, and consumption were observed.
• Air pollution levels decreased in many regions during the lockdown period.

Purpose of the Study:

• To quantitatively analyze the impact of travel restrictions on air quality in Northern China.
• To determine the extent to which reduced human mobility affected air pollution.
• To understand the mediating role of human movement in air quality changes.

Main Methods:

• Utilized daily air pollution data from 44 cities in Northern China (January 1 - March 21, 2020).
• Employed Baidu's Intracity Migration Index (IMI) to track human mobility.
• Conducted quantitative analysis to correlate travel restrictions with air quality changes.

Main Results:

• Air Quality Index (AQI) decreased by an average of 7.80%.
• Specific pollutants SO2, PM2.5, PM10, NO2, and CO reduced by 6.76%, 5.93%, 13.66%, 24.67%, and 4.58% respectively.
• Human movement reduction of 69.85% was observed, partially or fully mediating pollutant level decreases.

Conclusions:

• Travel restrictions during the COVID-19 pandemic were strongly associated with improved air quality.
• Human mobility is a key factor influencing air pollution levels, as demonstrated by the lockdown's effects.
• Findings underscore the significance of green production and consumption in mitigating environmental impact.