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How air pollution exacerbates Covid-19

There’s a relationship between air pollution and coronavirus, which may mean that tackling air pollution will be a crucial part of easing lockdown.

Researchers in the US are building a case that suggests air pollution has significantly worsened the Covid-19 outbreak and led to more deaths than if pollution-free skies were the norm. As well as predisposing the people who have lived with polluted air for decades, scientists have also suggested that air pollution particles may be acting as vehicles for viral transmission.

One recent study found that even small increases in fine particulate matter, known as PM2.5, have had an outsized effect in the US. An increase of just 1 microgram per cubic metre corresponded to a 15% increase in Covid-19 deaths, according to the researchers, led by Xiao Wu and Rachel Nethery at the at the Harvard University T.H. Chan School of Public Health.


The evidence we have is pretty clear that people who have been living in places that are more polluted over time, that they are more likely to die from coronavirus – Aaron Bernstein

For comparison, the safe limit designated by the US’s Environmental Protection Agency is 12 micrograms PM2.5 per cubic metre, while the World Health Organization has a guideline figure of 10 micrograms per cubic metre as an annual mean. Parts of New York have annual PM2.5 levels consistently above this safe threshold. Researchers suggest that this could have played a part in the scale of New York State’s coronavirus outbreak, with deaths as of April by far the highest of any state.

Child walks outside. Coronavirus theme. Girl in a skate.

“The evidence we have is pretty clear that people who have been living in places that are more polluted over time, that they are more likely to die from coronavirus,” says Aaron Bernstein, the director of the Center for Climate, Health, and Global Environment at Harvard University.

In the study, which looked at 3,080 counties in the US, people who had lived in counties with long-term pollution exposure for 15-20 years had significantly higher mortality rates, says Wu.

While the study has yet to be peer-reviewed by independent experts, Wu says that the association is likely down to the higher risk of existing respiratory and heart diseases in areas of higher pollution. Air pollution is also known to weaken the immune system, compromising people’s ability to fight off infection, according to the European Public Health Alliance.

“If Manhattan had lowered its average particulate matter level by just a single unit, or one microgram per cubic meter, over the past 20 years, the borough would most likely have seen 248 fewer Covid-19 deaths by this point in the outbreak [4 April 2020],” the researchers conclude.

A study of air quality in Italy’s northern provinces of Lombardy and Emilia Romagna also found a correlation between Covid-19 mortality rates and high levels of pollution. Lombardy makes up the vast majority of the country’s deaths, at 13,325 of Italy’s 26,644 as of 26 April, while Emilia Romagna was the province with the next greatest death toll, at 3,386. The researchers questioned the role of low air quality in their becoming hotspots, concluding that: “the high level of pollution in northern Italy should be considered an additional co-factor of the high level of lethality recorded in that area”.

You could pick any city in the world and expect to see an effect of air pollution on people’s risk of getting sicker from coronavirus – Aaron Bernstein

These are not the first studies to highlight a substantial link between air pollution levels and deaths from viral diseases. A 2003 study found that patients with Sars, a respiratory virus closely related to Covid-19, were 84% more likely to die if they lived in areas with high levels of pollution.

“For every small increment in air pollution, there’s a substantial increase in death,” says Harvard’s Aaron Bernstein. “You could pick any city in the world and expect to see an effect of air pollution on people’s risk of getting sicker from coronavirus.”

What’s more, another preliminary study detected Sars-CoV-2 (the virus that causes Covid-19) could even be hitching a ride on PM10 particles – the same stuff as PM2.5, just in slightly larger particles. The researchers, based at several universities across Italy, suggest the virus could be dispersed more widely on air pollution particles. But, like much research on coronavirus so far, this study too has yet to go through robust peer-review.


These findings could have a significant impact on how governments choose to ease lockdown restrictions and public health officials allocate medical resources such as ventilators.

Dirty air is preventing people of colour, in low-income communities in particular, from being able to have a fighting chance against this pandemic – Gina McCarthy

In the short-term, the findings could incentivise polluted countries which have not yet suffered severe outbreaks to adopt preventive measures. “They could take extra precautions, for example more stringent social distancing measures,” Wu suggests.

The Harvard researchers say their findings are particularly important for poor minority communities, who tend to be more exposed to air pollution, contributing to a higher risk of becoming seriously ill from coronavirus. 

In the US, some ethnic minorities are disproportionately exposed to air pollution, primarily caused by the consumption by white Americans, according to a 2018 study. Black and Hispanic people are typically exposed to 56% and 63% more PM2.5 pollution than they produce through consumption and daily activities. In sharp contrast, non-Hispanic white people are typically exposed to 17% less pollution than they produce. African Americans are also more likely than white Americans to have underlying health conditions, such as diabetes or heart disease, a disparity linked to a long legacy of social inequality.

Today we recognise that the world can change on a dime – Gina McCarthy

“Dirty air is preventing people of colour, in low-income communities in particular, from being able to have a fighting chance against this pandemic,” says Gina McCarthy, president of the Natural Resources Defence Council in the US.

Lifting lockdown

As lockdowns have shut down factories and kept cars off the roads, global pollution levels have fallen drastically. According to this year’s Air Quality Index, cities with historically high levels of PM2.5 have witnessed a dramatic drop in pollution since enforcing lockdowns; 44% in Wuhan, 54% in Seoul and 60% in New Delhi.

Some Facts about India’s Air Pollution


1. Worsening air quality is a pan-India problem: 76 percent of Indians live in places that do not meet national air quality standards. This means that air pollution in India is not a problem restricted to winters in Delhi or to India’s cities; in fact, no Indian state achieves pollution levels at or below the World Health Organisation’s (WHO) limits.

2. Air pollution is a leading risk factor for death: One in eight deaths in India was attributable to air pollution in 2017. Additionally, at 1.24 million, the deaths caused by air pollution are more than those caused by diarrhoea, tuberculosis, HIV, or malaria. The health cost of this is as high as USD 80 billion.

3. The elderly are disproportionately affected: About half of these 1.24 million deaths are of people over the age of 70, making the elderly among the most vulnerable to air pollution, in addition to women, children, and low-income communities.

4. The average life expectancy of a child is reduced by at least 2.6 years. Additionally, 10 percent of all under-five deaths in 2016 were caused by worsening air quality.

5. Low-income populations are overexposed to causes of air pollution because they do not possess the financial strength to defend themselves against it. This is because of four reasons:

  • They typically cannot afford to live in relatively safe or upwind residential areas, away from industry and powerplants.
  • They cannot afford new technology such as air purifiers and appropriate face masks.
  • They often have to take up jobs in mining, traffic management, or work as industrial labourers which overexposes them to higher amounts of particulate matter.
  • They are reliant on polluting fuels such as wood, dung, or kerosene for cooking and heating.

6. It is a public health emergency: New research indicates that air pollution impacts birth weight, child growth, obesity, and bladder cancer. There is growing evidence of the adverse impacts of pollution on cognitive abilities in children.

7. Rural India is being sidelined: Of the 600-plus air quality monitoring stations the Central Pollution Control Board (CPCB) set up across the country, there are none in rural areas. The lack of adequate monitoring and measurement systems leaves the air quality challenges in rural India uncovered.

8. Efforts aren’t reaching the people who need them the most: 49 of the 54 (90 percent) organised citizen mobilisations on air pollution in 2019 occurred in urban areas. 1 However, 75 percent of the deaths linked to air pollution (in 2015) occurred in rural areas.

9. Information about it is inaccessible: 84 percent of the total media coverage on air pollution is in English. 2

10. India has more polluted cities than any other country: 22 of the 30 most polluted cities in the world are in India, and almost 99 percent of Indians breathe air that is above the WHO’s defined safety limits.

Causes of indoor air pollution: Indian families have to be aware that pollution isn’t just caused by factors outside of their control. There are many facets of indoor pollution that can be controlled by them to make the quality of air their loved ones breathe better. Most Indians cook their meals on open fires using traditional methods such as wood, charcoal, cow dung and crop wastes that fill their homes with noxious smoke and toxicity. Other household products such as varnishes, paints and many cleaning products also emit polluted gases that can cause serious breathing problems. There is an urgent need to educate masses about their habits and the products they use and the health effects their malpractices can have.  

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