Study estimates the proportion of COVID-19 deaths due to air pollution

Reviewed by Emily Henderson, B.Sc.Nov 3 2020

Long-term exposure to air pollution generated by human activity is linked to about 27 per cent of COVID-19-related deaths in East Asia and 15 per cent mortality in South Asia and worldwide. These deaths could be largely prevented by adopting air quality regulations, says a new study.

Published in Cardiovascular Research on 27 October, the study estimates for each country the proportion of deaths from coronavirus that could be attributed to anthropogenic pollution.

Ninety-one per cent of the world's population lives in places where air quality exceeds the World Health Organization guideline limits. Around 2.3 billion people in the Asia Pacific region, which has some of the highest recorded levels of air pollution, are exposed to air pollution levels several times the WHO guideline for safe air.

Anthropogenic air pollution exacerbates chronic diseases, such as cardiovascular and pulmonary diseases, that act as precondition and aggravate the course of COVID-19 disease. This comorbidity increases the risk of mortality from the coronavirus."

Jos Lelieveld, Study Co-Author and Professor, Max Planck Institute for Chemistry and The Cyprus Institute in Nicosia

In addition, Lelieveld notes, the aerosol particles, which are micro-droplets that contain the virus, are generated by breathing and speaking (and especially by singing).

The researchers characterized global exposure to fine particulate matter of 2.5 microns or less in diameter (PM_2.5), based on satellite data, and calculated the anthropogenic fraction with an atmospheric chemistry model.

"When people inhale polluted air, the PM_2.5 migrates from the lungs to the blood vessels. This causes damage to the inner lining of arteries, the endothelium, and leads to the narrowing and stiffening of the arteries."

"The COVID-19 virus also enters the body via the lungs, causing similar damage to blood vessels, and it is now considered to be an endothelial disease," says co-author Thomas Münzel from the University Medical Centre, Johannes Gutenberg University and the German Centre for Cardiovascular Research, Mainz.

Czech Republic tops all countries on the percentage of COVID-19 mortality attributed to all anthropogenic emissions with 29 per cent and followed by Poland with 28 per cent. China and North Korea came in third at 27 per cent.

Bangladesh leads South Asia with 23 per cent (beating Bhutan's 21 per cent and India's 17 per cent), while Lesotho posted the highest figure for Africa at 20 per cent edging South Africa and Swaziland both with 18 per cent. Topping South America are Ecuador and Paraguay both with 15 per cent.

Globally, around half of the attributable man-made air pollution cause is related to fossil fuel use. It is up to 70-80 per cent in Europe, West Asia and North America.

"The switch from fossil to clean, renewable energy sources is a highly effective health promotion intervention. For example, in Europe, emissions control could save around 400,000 lives. The WHO recommends 10µg/m2 in Europe and we have 25µg/m3. We need new guidelines lowering the limits for PM_2.5," Münzel tells SciDev.Net.

There is limited representation of low-income countries in the study's findings. The data for the study has been collected only from middle- and high-income countries, but the calculations are carried out for the whole world.

"This study adds COVID-19 to the list of infectious diseases possibly exacerbated by air pollution. The development transition in many countries is accompanied by hazardous levels of exposure to air pollution from diverse sources, including transport and energy generation, and also agricultural burning and domestic cooking and heating," says Guy Marks, head of the Respiratory and Environmental Epidemiology group, Woolcock Institute of Medical Research, Sydney.

"These countries face a double jeopardy in dealing with the public health challenge of controlling COVID-19 transmission and its consequences for health services and the economy, and controlling emissions. We need global action to combat this hazard," Marks adds.