9 of 10 key global cities experienced significant PM2.5 reductions from the same period in 2019

Ten major global cities have been studied in the IQAir report for their relatively high number of coronavirus cases and government-mandated COVID-19 lockdown measures. In 7 of these identified cities, drastic restrictions on people’s movement and economic activity imposed during lockdowns resulted in PM2.5 reductions of 25-60%, as compared to the same time period last year.

This report analyzes levels of PM2.5 reported by ground-level monitoring stations in 10 major global cities. The data is based on a 3-week period for each city during lockdown conditions, and compares this to the same time period in 2019, 2018, 2017 and 2016. The same time period across different years was chosen, because air pollution levels often vary greatly with seasonal changes in weather and other conditions. The 3-week timeframe has been selected for each city to re ect either the period when the most stringent lockdown measures were in place or, during longer lockdown periods such as in Wuhan, to coincide with the ‘peak’ of daily reported COVID-19 cases. Cities were selected based on the extent of lockdown measures and the number of coronavirus cases relative to other cities in the same country. The methodology and data representation strives to highlight the effects of the COVID-19 lockdowns on a wide variety of cities with different air quality challenges.