Significantly More COVID-19 Deaths Are Occuring In US Communities With Higher Air Pollution Levels
Maps show (top) county level 17-year long-term average of PM2.5 concentrations (2000-2016) in the US in ug/m3 and (bottom) county level number of COVID-19 deaths per one million population in the US up to and including April 4, 2020.

People with COVID-19 are dying at significantly higher rates in communities in the United States with higher air pollution levels, according to a new Harvard University study  – the first such study to systematically examine links between air pollution and higher COVID-19 mortality. 

For every 1 microgram/ cubic meter (µg/m3) increase in average annual levels of fine PM2.5 particle pollution, COVID-19 death rates as of 4 April, 2020 were 15% higher, according to the pre-print study of death rates across some 3,080 counties of the United States, where 98% of the US population resides, by a group of researchers from the Harvard Chan School of Public Health, published Tuesday.

The strong association between higher average levels of air pollution over the past 20 years, and higher mortality rates in the ongoing COVID-19 emergency was observed even at comparatively low average annual air pollution exposure levels, of just 2-12 µg/m3 of PM 2.5.

In comparison, WHO guideline limits for PM2.5 concentrations are 10 µg/m3 annual average, although the Agency has long observed that health effects from air pollution are also observed at much lower levels.  PM 2.5 levels in some major European cities often exceed the WHO guidelines by as much as 5-10  µg/m3 or more, while air pollution levels in many low and middle-income cities may be 5-10 times above the WHO guideline levels.

The association between slighty higher levels of air pollution and much higher rates of COVID-19 mortality held firm, even after data was adjusted for a range of other variables that can also influence COVID-19 mortality such as population age and poverty rates; smoking and obesity prevalence; as well as health services availability and rates of COVID-19 testing.

“A small increase in long-term exposure to PM2.5 leads to a large increase in COVID-19 death rate, with the magnitude of increase 20 times that observed for PM2.5 and all cause mortality. The study results underscore the importance of continuing to enforce existing air pollution regulations to protect human health both during and after the COVID-19 crisis,” said the researchers, members of the Department of Biostatistics

Moreover, the association seemed to be cumulative – at least at the comparatively lower levels of air pollution common in the United States. So while higher average annual PM2.5 concentrations of 1 µg/m3 was associated with a 15% greater mortality rate, PM2.5 levels just 2 µg/m3 higher, would be associated with a 30% higher rate of COVID-19 mortality, and so on.

“We hypothesize that because long-term exposure to PM2.5 adversely affects the respiratory and cardiovascular system, it can also exacerbate the severity of the COVID-19 infection symptoms and may increase the risk of death in COVID-19 patients,” the authors concluded. “The association between PM2.5 and health including pregnancy outcomes, respiratory diseases, cardiovascular diseases, neurocognitive disease in the United States and worldwide is well established.”

Some 248 Lives Could Have Been Saved In Manhattan Alone

At the New York City epicenter of the pandemic, the researchers found that some 248 lives could have potentially been saved, so far,in the borough of Manhattan, alone, if average air pollution levels over the past 20 years had been just 1 µg/m3 lower.

Similar associations have been found for death rates in Italy, according to a another new review published by European researchers in the Environmental Pollution journal.  The study by researchers from the University of Siena and Aarhus University noted that COVID-19 mortality rates were highest in Italy’s most polluted regions, Lombardy and Emilia Romagna, at 12% compared to 4.5% in the rest of the country. However that review did not examine death rates as systematically as the Harvard study, or did it analyse against other confounders, including age, other health risk factors, and access to health services. 

Other studies of “before” and “after” pandemic satellite images have also noted that one big bonus of the COVID-19 crisis has been the cleaner skies observed over many parts of the world, from highly polluted parts of northern Italy to India and China. However, environmental health experts worry that those gains will be only temporary unless policy makers recognize more widely the huge health penalty imposed by chronic air pollution exposures -which WHO estimates kill some 7 million people every year.

On March 30, the European Public Health Association (EPHA) warned that years of exposure to air pollution may have left patients with pre-existing heart or lung conditions, rendering them more vulnerable to COVID-19. 

The statement was accompanied by satellite images showing nitrogen dioxide (NO2) air pollution levels over the Americas, Europe and Asia in March 2020 as compared to March 2019, to illustrate the blue skies impacts of COVID-19.  But the The damage is already done. Years of breathing in dirty air from traffic fumes and other sources will have weakened the health of all those who are now embroiled in a life or death fight against COVID-19,” warned Sascha Marschang, acting secretary general of the EPHA in a statement

Images combine NO2 emission readings from 5-25 March in 2019 versus the same period in 2020, based on ESA Sentinel-5 satellite data, following recommended image processing guidelines. Image credits: ESA / EPHA / James Poetzscher

Air pollution exposures lead to  chronic inflammation of the lungs, even in young and healthy subjects, and exposures over time increase the risk of acute respiratory distress syndrome – a severe manifestation of COVID-19 that leads to death, according to the authors of the European paper. Air pollution is also a factor in cardiovascular disease and stroke, as fine particles enter the blood stream as well, causing inflammation, hypertension, and increasing risks of blood clots. 

The link between COVID-19 mortality and the range of air-pollution related chronic diseases has already been well-established. Significantly higher proportions of people with acute and chronic respiratory disease, lung cancer, heart disease, and stroke, are hospitalized and eventually die from COVID-19.   But the Harvard study establishes an even more direct link.  

“The results of [our] study underscore the importance of continuing to enforce existing air pollution regulations during the COVID-19 crisis,” Harvard researchers Xiao Wu, Rachel Nethery, Benjamin Sabath, Danielle Braun, and Francesca Dominici wrote. “We anticipate a failure to do so can potentially increase the COVID-19 death toll and hospitalizations.” 

The Harvard paper was published just days after the US Administration of Donald Trump relaxed emissions requirements on new vehicles for the coming years, and just ten days after the US Environmental Protection Agency (EPA) relaxed reporting requirements for not only for air pollution emissions from factories and power plants, but also for emissions of effluents and hazardous waste materials, citing the COVID-19 emergency. The new policy sparked fears that polluters were now given a “free for all” to increase emissions, although the US EPA has since pushed back on that claim.

In one bright spot, the lower levels of nitrogen dioxide (NO2) and particulate matter (PM) from road traffic may bring “some relief” to patients currently stricken with coronavirus, according to the EPHA.

Iran & Other Countries Consider Gradual Relaxation of Lockdown 

In other developments, Iran, which has been the Eastern Mediterranean Region’s COVID-19 epicentre, may relax its nationwide business shutdown by Saturday, allowing for the resumption of  “low-risk” activities, said President Hassan Rouhani in a televised meeting. The country has been reporting about 100 fewer new cases per day over the past week. Still, 2100 new cases were reported today, and Iran remains the hardest hit country in the region, with a cumulative total of 62,589 total cases and 3,872 total deaths as of Tuesday night.

Iranian health worker disinfects bus.

In Europe, The Czech Republic announced that it would also relax lockdown measures from next Tuesday, reopening some shops and industries, and allowing limited travel abroad. The country of 10.65 million people currently has recorded 4944 cases and 87 deaths, less than a fifth of Switzerland, which has only 8.5 million people. 

Wuhan city in Hubei, China, the original epicentre of the COVID-19 pandemic, also announced that it would finally lift lockdown measures on Wednesday after more than two months in whch residents have been besieged by the virus, according to a notice posted by provincial authorities. Economic recovery is the next challenge, said Hu Chaowen, director of Hubei Province’s Poverty Alleviation Office at a press conference. He calling 2020 “the year of a decisive battle against poverty,” alluding to the economic hardships experienced by poor and day wage laborers.

In other pandemic hotspots, however,  lockdown measures were still being tightened as cases continued increasing. 

Authorities in Switzerland called on the public to maintain social distancing, saying it is too early to tell if the slowdown in new infections meant that the apex had been reach. Total COVID-19 deaths rose from 590 to 641 over the past 24 hours in a country that has 22 242 confirmed cases, for one of the the highest incidence rates of COVID-19 in Europe (259 cases/100 000 people). 

Despite initial signs that new case counts in key countries such as the United Kingdom, Italy, France and Spain, were stabilizing, others were still seeing sharp daily increases. Turkey reported some 3,148 new cases on Tuesday, for a total of 30,217. And The Republic of Belarus, which until now had very few cases at all, reported 794 total cases on Tuesday, as compared to 562 the day before.  

In an urgent attempt to stave off a wider outbreak in Belarus, a special WHO Delegation will arrive today by invitation from the President of Belarus Aleksandr Lukashenko. The Delegation will “assess the real situation, adequacy and efficiency of measures taken to prevent the spread of coronavirus the country, as well as to analyze clinical protocols and approaches to medical care”, says the National State TV and Radio Company of the Republic of Belarus. 

In the US, New York State doubled the maximum fine for violations of the state’s social distancing protocol and extended the closure of nonessential businesses and schools until the end of the month, according to a Tuesday press release from the Governor’s office. Some 1000 beds aboard the US Navy’s hospital ship the Comfort were made available to treat COVID-19 patients, following requests from New York officials to expand the ship’s mission. 

New York City experienced the “largest single day increase” in death toll of 731 deaths, said Governor Andrew Cuomo in a press briefing Tuesday. On a more positive note, however, the Governor added that the three-day average of daily hospitalization rate is reducing, and that the number of daily intensive care admissions is also “way down.

Total cases of COVID-19 as of 6:04 PM CET, with active case distribution globally. Numbers change rapidly.
WHO Maintains Position that Public Mask Use Unnecessary- Despite Increasing Evidence of Airborne Virus Transmission

In updated guidance, issued Tuesday, WHO continued to maintain that evidence of virus transmission as very fine “aerosol” particles was insufficient to justify universal use of masks by the public. However, that position is being challenged by a number of leading experts who say such airborne transmission is a possibility, and that masking helps protect healthy individuals from others who may unknowingly be COVID-19 carriers. 

While WHO has contended that the virus can only be transmitted effectively by droplets released through coughing or sneezing, Tang and other experts believe that it may also be transmitted by even tinier aerosol particles, released through the simple acts of breathing or speaking.

And since many people anyway don’t know if they are infected, universal masking would ensure that infected individuals don’t transmit transmission of the virus to other, healthy people, who are in their close proximity.

“The assumption should be that airborne transmission is possible unless experimental evidence rules it out, not the other way around”, said virologist Julian Tang at the University of Leicester, writing for Nature“If everyone can mask, it is double, two-way protection,” Tang added

Improving ventilation indoors or banning indoor meetings could be other measures helpful to preventing aerosol transmission, said scientist Lidia Morawska from the Queensland University of Technology in Australia in the Nature article.

WHO has also expressed concerns that public adoption of masks would create even greater shortages of protective equipment for health care workers, who are already desperately short. However, some health authorities, including the US Centres for Disease Control and Israel’s Ministry of Health, are also recommending that people fabricate their own cloth masks, which can be washed and reused. 

If the most vulnerable populations are guaranteed masks, the wider public could adopt masks as well, suggests Ben Cowling, an epidemiologist at the University of Hong Kong.

WHO’s Scientific brief acknowledges that airborne transmission of the virus “may be possible,” but it is limited to certain specialized medical procedures. That position is anchored in a WHO analysis of 75,465 COVID-19 cases from China from mid-February, which found that airborne transmission was “not reported.” 

“There is currently no evidence that wearing a mask (whether medical or other types) by healthy persons in the wider community setting, including universal community masking, can prevent them from infection with respiratory viruses, including COVID-19,” the WHO guidance states.

“The wide use of masks by healthy people in the community setting is not supported by current evidence and carries uncertainties and critical risks”. Medical masks should be reserved for healthcare workers. Only persons with symptoms or health personnel working under “aerosol-generating procedures” should use a mask, advises the WHO.

Commuters wear masks to protect against transmission of COVID-19 on a train in Singapore

-Svĕt Lustig Vijay and Gauri Saxena also contributed to this story


Image Credits: Wu et al. "Exposure to air pollution and COVID-19 mortality in the United States," Harvard University, Mina Noei, Jade Lee .

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