Did the COVID-19 lockdowns reduce air pollution in Lombardy?

Air pollution is currently the most important environmental risk to human healt in Europe [1]. Exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) increases mortality rates and hospitalizations due to respiratory and cardiovascular disease [2]–[7], and it leads to a decline in physical and cognitive productivity [8]–[12].

Lombardy is one of the most polluted regions in OECD countries. Did its inhabitants breath cleaner air during the COVID-19 lockdown from March 6 to May 4, 2020?

Using a machine-learning algorithm, researchers at the the European Institute on Economics (EIEE) and the Environment, Bocconi University and Politecnico di Milano estimated that the lockdown from March to May reduced background concentrations of PM2.5 by 3.84 µg/m3 (16%) and NO2 by 10.85 µg/m3 (33%). Nonetheless, the improvement in air quality saved at least 11% of the years of life lost and 19% of the premature deaths attributable to COVID-19 in the region during the same period.

Health benefits of improved air quality
PM 2.5 NO2
Avoided premature deaths/100.000 inhab 10.2 to 24.8 28.8
as % of COVID-19 premature deaths 6.5% to 16% 18.60%
Years of life saved/100.000 inhab 72.1 to 175.9 203.7
as % of COVID-19 years of life lost 3.8% to 9.3% 10.8%

Avoided premature deaths and years of life saved for PM 2.5 are calculated using hazard ratios from Krewski et al. (2009) (lower bound) and Lepeule et al. (2012) (upper bound). Calculations for NO2 use an hazard ratio from Henschel et al. (2018). Avoided premature deaths are calculated using the population-weighted change in concentrations at background stations. Given the high correlation between concentrations of PM2.5 and NO2, the concentration-response function of these pollutants are interdependent. It is recommended that avoided deaths and YLS be not aggregated across pollutants, lest incurring in partial double counting. For comparison, in Lombardy, from February 22 to May 3 2020, every 100,000 people 155 died after testing positive for COVID-19 and 1891 years of life have been directly lost to the virus.

Concentrations of PM2.5 and NO2 since November

The same methodology is applied to track the effect of the second COVID-19 lockdown on concentrations of PM2.5 and NO2.


The methodology is described in COVID-19 lockdown only partially alleviates health impacts of air pollution in Northern Italy, by Francesco Granella, Lara Aleluia Reis, Valentina Bosetti and Massimo Tavoni, published on Environmental Research Letters.


Francesco Granella - Bocconi University and RFF-CMCC European Institute on Economics and the Environment

Lara Aleluia Reis - RFF-CMCC European Institute on Economics and the Environment

Valentina Bosetti - Bocconi University and RFF-CMCC European Institute on Economics and the Environment

Massimo Tavoni - Politecnico di Milano and RFF-CMCC European Institute on Economics and the Environment


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