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PHOTO: aj NAKASONE, PEXELS.COM

The flip side of the new Coronavirus outbreak - reduced air pollution mortalities?

News - News from CICERO

Published 09.03.2020

In February, air pollution over large parts of China was reduced by 20 to 30 percent (1). If air pollution levels remain this low for a longer-term period, 50,000 - 100,000 premature deaths could be avoided according to calculations by CICERO, Norway's leading institute for climate research.

Protection of the most vulnerable among us is a main reason why we take action to combat the new Coronavirus. Protection of the most vulnerable is also at the core of the Air Quality Guidelines set by the World Health Organization. Whilst being a non-infectious ‘silent killer’, the timely concern for vulnerable groups should be a reminder and should motivate regulatory authorities in all countries where the Air Quality Guidelines are exceeded to strengthen their air pollution policies.

Reports on how the new Coronavirus (Covid-19) outbreak is affecting supply chains and disrupting business and manufacturing operations around the world are increasing day by day (2). As a consequence of current efforts by the Chinese government to quarantine a large number of its population and the reduced economic activity, emissions of air pollution seem to be plummeting as well.

Without diminishing the huge impact on health and societies of the Covid-19 outbreak, we have looked at the number of deaths that may be avoided due to reduced air pollution. A simplified calculation shows that if the ambient concentrations of fine particulate matter (PM2.5) over China remains at a level 20 - 30% below the baseline situation for a full year, the annual avoided number of premature deaths could amount to 54,000 - 109,000. This corresponds to a 5 - 10% reduction of current annual air pollution related deaths (the assumption that the low levels will persist is uncertain). PM2.5 pollution is killing around 1.15 - 1.24 million people in China every year (3) (4).

Given a 20 - 30% reduction in ambient PM2.5 levels, the avoided number of premature deaths only in Hubei, the province where the virus first was discovered, amounts to 2,500 - 3,800.

The new Coronavirus has currently infected more than 110,000 people and killed nearly 4,000 globally, numbers that are growing rapidly (5). The outbreak was declared a Public Health Emergency of International Concern by the World Health Organization on 30 January 2020.

Copernicus, the European Union's Earth Observation Programme, tracked air pollution across most of China in February 2020 and compared it to data from the same month from the last four years. The comparison showed a decrease in surface levels PM2.5 of between 20 and 30 per cent over large parts of China, a reduction that can likely be attributed in part to the widespread lockdown following the outbreak of the coronavirus (1).

The avoided deaths are calculated applying a model for estimating health impact from PM2.5 pollution in China, using data for the air pollution exposure a few years back in time, and assuming that the outbreak of Covid-19 does not change households’ use of solid fuels for cooking and heating (3) (6). Solid fuel use still contributes substantially to population-weighted exposure to PM2.5 in China, partly through pollution indoors of people’s homes, and needs to be considered when calculating premature mortality to avoid overestimating the impact of reduced ambient air pollution (7).

More than 80% of the avoided premature deaths from reduced ambient PM2.5 pollution is estimated to occur in the group of people over 65 years of age. As is the case for the Covid-19 virus, the impact of PM2.5 pollution is higher among the most vulnerable parts of the population, including older adults and people with chronic diseases.  

References

(1) CAMS (Copernicus Atmosphere Monitoring Service) (2020). Amid Coronavirus outbreak: Copernicus monitors reduction of particulate matter (PM2.5) over China. 

(2) Haren, P. and Simchi-Levi (2020). How Coronavirus Could Impact the Global Supply Chain by Mid-March Harvard Business Review. 

(3) Aunan K, Ma Q, Lund MT, Wang S. (2018). Population-weighted exposure to PM2.5 pollution in China: An integrated approach. Environment International; 120: 111-120.

(4) IHME (Institute of Health Metrics and Evaluation) (2020). Global Burden of Disease 2017. University of Washington. 

(5) John Hopkins CSSE (2020). Coronavirus COVID-19 Global Cases. 

(6) Zhao B, Zheng H, Wang S, Smith KR, Lu X, Aunan K, et al. (2018). Change in household fuels dominates the decrease in PM2.5 exposure and premature mortality in China in 2005-2015. PNAS; 115: 12401-12406.

(7) Aunan, K. (2018). Exposure matters: Revisiting the current approach to air pollution health burden estimation. CICERO Climate News.