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As the novel coronavirus tears around the world, it’s exploiting our biggest weaknesses, from creaking health care systems to extreme social inequality. Its relationship with one pervasive and neglected problem, however, is more tangled: Air pollution has intensified the pandemic, but the pandemic has—temporarily—cleaned the skies.

When new evidence emerged this week that dirty air makes COVID-19 more lethal, it surprised no one who has followed the science of air pollution—but the scale of the effect was striking. The study, which must still undergo peer review for publication, found that the tiny pollutant particles known as PM2.5, breathed over many years, sharply raise the chances of dying from the virus.

Researchers from Harvard University’s T.H. Chan School of Public Health analyzed data on PM2.5 levels and COVID-19 deaths from about 3,000 U.S. counties covering 98 percent of the U.S. population. Counties that averaged just one microgram per cubic meter more PM2.5 in the air had a COVID-19 death rate that was 15 percent higher.

“If you’re getting COVID, and you have been breathing polluted air, it’s really putting gasoline on a fire,” said Francesca Dominici, a Harvard biostatistics professor and the study’s senior author.

That’s because the fine particles penetrate deep into the body, promoting hypertension, heart disease, breathing trouble, and diabetes, all of which increase complications in coronavirus patients. The particles also weaken the immune system and fuel inflammation in the lungs and respiratory tract, adding to the risk both of getting COVID-19 and of having severe symptoms.

Dominici and her colleagues illustrated the impact with a specific example: Manhattan, the current epicenter of the pandemic, where PM2.5 averages range as high as 11 micrograms per cubic meter, and where 1,904 deaths from COVID-19 had been reported as of April 4. Had particle levels averaged just one unit lower over the past two decades, the researchers calculated, 248 fewer people would have died over the past several weeks. And of course the toll has mounted since April 4.

But while pollution inhaled in the past is still causing harm today, the temporary experience of cleaner air brought about by widespread shutdowns may offer lessons for the kind of world we want to build after the pandemic.

People so accustomed to pollution they hardly think about it may realize, “Actually, I really do quite enjoy clean air: Do you think we could get it, or keep it?” says Simon Birkett, founder and director of Clean Air in London, an advocacy organization. “There’s a chance to really get people to stop, take a deep breath,” and reflect on questions like “How was your asthma during this period?”

Although a near-halt in normal life and economic activity is no one’s idea of a good way to reduce pollution, the brief respite might, in Birkett’s view, turn this dark time into “a catalyst, or a tipping point, which could get us to say ‘Clean air—there’s something special about it.’”

Cleaner pandemic skies

From China’s Hubei province to industrial northern Italy and beyond, pollution levels have plummeted as lockdowns aimed at slowing the viral spread have shuttered businesses and trapped billions of people at home. In India, where air pollution is among the world’s worst, “people are reporting seeing the Himalayas for the first time from where they live,” Lauri Myllyvirta, lead analyst at the Helsinki-based Centre for Research on Energy and Clean Air, said in an email.

India’s hastily imposed shutdowns have been devastating, leaving hundreds of thousands of migrant workers without homes or jobs. But in Delhi, where air is normally choking, levels of both PM2.5 and the harmful gas nitrogen dioxide fell more than 70 percent.

The declines are sure to be only temporary. To get healthier air for the longer term, Myllyvirta said, means shifting to clean energy and transportation, “not ordering people to stay at home at drastic economic cost.” But the cleaner pandemic skies do show how fast we can bring down pollution when we reduce our burning of fossil fuels.

The cleaner air is also a reminder of how deadly air pollution is. The World Health Organization says dirty air, both indoors and out, cuts short seven million lives annually worldwide.

In the United States, decades of regulation have led to air quality that is far better than in most of the world. In New York City, for example, PM2.5 levels actually fell 30 percent from 2009 to 2017, which has presumably saved many lives during the current pandemic. Nevertheless, air pollution still kills more than 100,000 Americans every year.

The realization that COVID-19 may match or even exceed that toll has rightly terrified Americans. But the lethal effects of air pollution are barely discussed—and activists and scientists are hoping that might change.

Pollution and COVID-19

Even before the new Harvard study, scientists were convinced that air pollution was likely worsening COVID-19’s impact, in addition to the wide-ranging health damage it causes on its own. A 2003 study of the outbreak of SARS, the closest relative of the new coronavirus, found that death rates in China’s most polluted areas were twice as high as in the least polluted ones.

“You could bet a fiver that London and other more polluted places will have higher mortality rates [from the virus], because there’ll be more people with underlying issues,” Birkett said. Scientists also believe viruses may bond with pollution particles, enabling them to remain in the air longer and helping them make their way into the body.

The flip side is that even temporarily cleaner air can help “flatten the curve” of the pandemic, easing the burden on health care systems by reducing the number of people who experience severe COVID-19 symptoms, said Christopher Carlsten, head of respiratory medicine at the University of British Columbia’s School of Population and Public Health, in Vancouver.

Cleaner pandemic skies should also reduce other pressures on hospitals struggling with COVID-19 cases, Carlsten said. In addition to the cumulative effects of breathing dirty air for years, a large body of evidence shows that short-term changes in air quality have an immediate impact on heart attacks, strokes, and emergency room visits. All increase when pollution spikes.

Authorities in British Columbia had that hope in mind when they issued restrictions on the fires farmers typically light at the start of spring to clear old growth from fields. One region in British Columbia even banned campfires. Wood smoke is thick with PM2.5 particles.

In China, the drops in pollution resulting from coronavirus shutdowns likely saved between 53,000 and 77,000 lives—many times more than the direct toll of the virus—according to calculations done by Marshall Burke, an Earth system scientist at Stanford University. That might sound surprising, but it shouldn’t be, he said, given that air pollution causes more than 1.2 million annual deaths in China. Indeed, a 2016 study found that China’s aggressive measures to clean the air in and around Beijing for the 2008 Olympics had led to a temporary 8 percent drop in the overall death rate.

Burke emphasized that in estimating the benefit of China’s less polluted air, he was in no way minimizing the cost or the horror of the pandemic. But “these other things we do, that we can change, are also important,” he said. “Lives we lose absent a pandemic are also really important, and are lives we shouldn’t lose.”

After the pandemic—what?

There’s no doubt the pandemic-driven clearing of the air will be short-lived, with emissions sure to return to, if not surpass, their usual levels whenever factories start up again and people get back in their cars.

That’s already happening in China, where pollution has returned to its pre-coronavirus range, Myllyvirta said, even though some industries are not yet fully operational—a worrying hint that air quality could end up worse than before, he added.

That’s a danger elsewhere too. When the pandemic finally abates, polluting industries may well seek to make up for lost time with even higher production, said François Gemenne, a political scientist and environmental researcher at the University of Liège, Belgium. If the virus makes people fearful of public transportation, driving could increase also.

What’s more, “a lot of governments will be inclined to restart their fossil fuel industry, because that is the industry that is immediately available,” Gemenne said. With recession looming and credit markets taking a hit, analysts say investment in wind and solar power is likely to sag.

Economic troubles often prompt governments to loosen health-protective regulations. In the United States, the Environmental Protection Agency has cited the pandemic as justification for a decision to all but suspend enforcement of pollution rules. The Trump administration is also rolling back ambitious Obama-era auto mileage standards, and unraveling other regulations too.

In the middle of a health emergency, it’s exactly the wrong move, said Susan Anenberg, associate professor of environmental health at the George Washington University. On the contrary, she argued, “it’s the time to be considering whether the status quo that we had in place prior to this disaster is the one we want going forward. We don’t need to tolerate this level of air pollution.”

An earlier version of this story misstated the status of the Harvard study. It has been submitted for peer review but has not been "fast-tracked" for publication at the New England Journal of Medicine.

A pair of photos from Ahwaz, Iran, that were included in an earlier version of this story have been removed. Although parts of Iran have indeed seen declines in air pollution as a result of the response to the pandemic, those photos did not show that effect.

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Pollution made the pandemic worse, but lockdowns clean the sky

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Even before the coronavirus, air pollution killed seven million people a year. Will today’s cleaner air inspire us to do better?

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Influenza 1918 | Article

The 1918 Influenza Pandemic and COVID-19

Much has changed since the influenza pandemic of 1918, yet our responses to COVID-19 must still rely on many of the century-old lessons.

The source of the influenza illness remained a mystery to scientists as viruses were too small and obscure for the optical microscopes available in 1918. Credit: Naval Historical Society

Pandemic. The word originates from the Greek word pandēmos - meaning from 'all' ( pan) 'people' ( dēmos). Today, the word conjures many frightening images but holds similar meaning - a geographically widespread or global malady, generally with regard to infectious disease outbreaks. Indeed, for centuries, novel diseases and pathogens have emerged to produce pandemics in human populations, causing widespread illness and death, as well as economic, social and political disruptions.

The ancient Greeks believed diseases to be of a spiritual origin - a punishment from the gods for wrongdoings. In the 5th century BCE, an outbreak characterized by sore throat, aches and respiratory distress was noted by Hippocrates and named " The Cough of Perinthus." In doing so, Hippocrates may have provided the first documented experience of perhaps the most notorious pandemic pathogen: influenza. Although it is unlikely that the Cough of Perinthus was the first influenza outbreak in humans, it is the first chapter or at least the prologue to a dramatic history of significant human influenza outbreaks. Medical historians believe large scale influenza outbreaks occurred in 1510 and 1557 that may have been pandemics, but an outbreak in 1580 marks what is widely regarded as the first true influenza pandemic. This pandemic caused upwards of 8,000 deaths in Rome and devastated cities in Spain - literally decimating some by killing one out of every 10 residents. Since that time, we have documented two additional influenza pandemics in the 18th century, another two in the 19th century, three in the 20th century and one thus far in the 21st century.

Of these, an influenza pandemic occurring in 1918 is the most infamous. Fueled by the transport of soldiers in the final stages of World War I, the outbreak quickly spread around the world in three distinct waves, infecting up to one-third of the people on earth and killing an estimated 50 to 100 million people. Infections were complicated with high rates of bacterial pneumonia, and the pandemic was characterized by a uniquely high mortality rate in young adults between 20 and 40 years of age. By the time the pandemic ended in 1920, it was the worst acute infectious disease outbreak in modern history and the greatest mortality event in the world since the Black Death - a 14th-century pandemic caused by the plague.

When young, healthy soldiers began getting sick by the dozens in March, 1918, military physicians were baffled by what might be causing it. Credit: National Archives and Records Administration

The 1918 pandemic had profound impacts on life in the United States. In October of 1918, some 195,000 Americans were killed by the outbreak. By the time it ended, over 600,000 had lost their lives, and thousands of children were orphaned. So dire was the situation that many cities including Boston, Richmond, St. Louis and others mandated quarantines and social-distancing measures. In San Francisco and Seattle, laws were passed forcing people to wear masks covering their mouths and noses while in public. The public health commissioner in Chicago told police to arrest anyone seen sneezing without covering their face in public.

These horrors were exacerbated by a number of factors. Many physicians and nurses were enlisted in the armed forces to aid in the efforts to win the First World War, leaving a depleted healthcare workforce. The outbreak stoked nativist reactions and the stigmatization of certain ethnic groups - such as anti-Italian sentiments in Denver - which limited the effectiveness of efforts to curtail the outbreak. There were also restrictions on communication and the flow of information. President Woodrow Wilson created the Committee on Public Information when the United States entered World War I, and at Wilson's urging, Congress passed the Sedition Act in 1918, which allowed for up to 20 years of imprisonment for criticizing the government or spreading information that could hamper the production of materials necessary for the war effort. To this end, the government printed materials urging people to report anyone " who spreads pessimistic stories...cries for peace, or belittles our effort to win the war" to the Justice Department. These greatly limited communication and delayed the public health response to the emerging health crisis For example, newspapers in Washington, D.C. did not begin reporting on the outbreak until the last week of August - months after it had begun.

Much has changed for the better since 1918. For one, after Dr. Richard Shope isolated the influenza virus in his laboratory in 1931, we now know that influenza is caused by a virus. We no longer need to exclusively rely on non-pharmaceutical interventions to respond to influenza pandemics because we have developed and refined our ability to create and produce safe and efficacious vaccines. Sir Alexander Fleming discovered penicillin in 1928, which opened the door for developing antibiotics that can help treat complications from influenza, such as pneumonia. There is now an entire field of diplomacy dedicated to health and responding to the global threats posed by infectious diseases. And we no longer name pandemics after geographic locations, people, animals or cultural references in efforts to avoid stigmatization.

However, there have also been changes since 1918 that complicate the responses to pandemics. A growing body of evidence suggests pandemics may occur more frequently due to changes in land use, exploitation of the natural environment and demographic trends like urbanization-all of which increase the risk of infectious disease outbreaks. Today's society is also undoubtedly more globalized than that of 1918. The World Health Organization estimates that our world is so interconnected, a pathogen could conceivably spread around the world in 36 hours. Simulations suggest that if a highly contagious and lethal pandemic similar to the 1918 influenza were to occur today, approximately 33 million people could die in 6 months.

Presently, we find ourselves in the midst of another pandemic. In December of 2019, a novel virus emerged in China and quickly spread throughout the country and the world, causing a disease called COVID-19, which stands for Coronavirus Disease 2019. Similar to the 1918 influenza, COVID-19 is a respiratory disease and pneumonia can be a complication. It has emerged in a time characterized by rising sentiments of nationalism and isolationism, and one in which the role of the media is in the spotlight. The spread of the disease has been fueled by the transportation of people around the world. And while we currently do not know exactly how contagious or deadly COVID-19 is, because we do not yet know the true number of persons infected, estimates based on available data suggest that it has the potential to rival the 1918 influenza.

The United States Public Health Service issued this pamphlet in October of 1918 as part of a public education campaign to slow the progress of the disease. Credit: Library of Congress, Rare Book and Special Collections Division

In the absence of pharmaceutical treatments and therapies for COVID-19, the response to the virus has relied heavily on non-pharmaceutical interventions and supportive treatment, much like the response to the 1918 influenza. Similarly, the response to COVID-19 has also witnessed the implementation of dramatic social distancing measures in cities, the passing of new policies designed to curtail the spread of disease and the stigmatization of people and culture that hinder the public health response.

The 1918 influenza pandemic was a pandemic in every sense of the word - global and affecting all people, from poor factory workers to world leaders like President Wilson. However, for all of the horrors that the 1918 influenza pandemic brought with it, the outbreak eventually came to an end and brought opportunities to learn and prepare for future pandemics. While our current situation is frightening, COVID-19 can be controlled through public health interventions, much as the influenza pandemic was eventually contained. The century-old lessons are clear: we must act swiftly, intentionally and implement multiple interventions simultaneously to curb the spread of disease.

Matthew Boyce

Matthew Boyce (@mattrbo) is a Senior Research Associate at the Center for Global Health Science & Security at Georgetown University. His research is focused on global health security, sustainable capacity development, and public health preparedness-especially at the local and sub-national levels.

Rebecca Katz

Dr. Rebecca Katz (@RebeccaKatz5) is a Professor and Director of the Center for Global Health Science and Security at Georgetown University Medical Center. She teaches courses on global health diplomacy, global health security, and emerging infectious diseases in the School of Foreign Service. Since 2007, much of her work has been on the domestic and global implementation of the International Health Regulations as well as global governance of public health emergencies.

[1] These restrictions also contribute to why 1918 influenza pandemic is commonly called the 'Spanish Influenza.' Spain was neutral in the First World War and did not censor its press. Thus, it was one of the only countries reporting on the pandemic at the time and as a result, thought to be where the outbreak began in 1918 despite the fact that modern evidence suggests the outbreak likely began at a U.S. Army camp in Kansas and had already been circulating in the United States of America for months.

Sources

Georgios PappasabIsmene, J.KiriazeacMatthew, E.Falagas,Insights into infectious disease in the era of Hippocrates (ScienceDirect)

Patrick R. Saunders-Hastings and Daniel Krewski,Reviewing the History of Pandemic Influenza: Understanding Patterns of Emergence and Transmission(Pathogens)

C.W. Potter,A history of influenza (Journal of Applied Microbiology)

Andrew Milsten, 1918 Influenza Pandemic: A United States Timeline (American College of Emergency Physicians)

J. Alex Navarro, Alexandra Stern, Howard Markel (eds.), The American Influenza Epidemic of 1918: A Digital Encyclopedia

Alan M. Kraut, Immigration, Ethnicity, and the Pandemic (Public Health Reports)

David W. Seitz, World War I, Mass Death, and the Birth of the Modern US Soldier: A Rhetorical History

WHO, World Health Organization Best Practices for the Naming of New Human Infectious Diseases

Global Preparedness Monitoring Board, A World at Risk: Annual report on global preparedness for health emergencies

Bill Gates, Shattuck Lecture

Helen Branswell and Andrew Joseph, WHO declares the coronavirus outbreak a pandemic (STAT)

Howard Markel, Harvey B. Lipman, J. Alexander Navarro, et al, Nonpharmaceutical Interventions Implemented by US Cities During the 1918-1919 Influenza Pandemic (JAMA)

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The 1918 Influenza Pandemic and COVID-19 | American Experience | PBS

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Influenza 1918 | Article Much has changed since the influenza pandemic of 1918, yet our responses to COVID-19 must still rely on many of the century-old lessons. Pandemic. The word originates from the Greek word pandēmos - meaning from 'all' ( pan) 'people' ( dēmos).

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From this article I learned that the 1918 influenza pandemic was very similar to Covid 19. There were social distancing measures and people had to wear masks over their mouth and noses. I thought it was really interesting to see how we are still using the same techniques we used in 1918.

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I learned that the 1918 flu pandemic infected one third of the world population, and that it killed around 50 to 100 million people. Today, there is evidence that pandemics will become more common as urbanization increases.

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I learned about the 1918 influenza and how they used lots of non pharmaceutical interventions, this is similar to COVID-19 because there is no vaccine yet. They are using the same tactics to fight back COVID-19 today as they did with the 1918 influenza, we need to act fast and implant interventions.

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Pollution and the COVID-19 pandemic both impact each other in different ways. One study found that in areas where the particle PM 2.5 is inhaled, the chance of death is much higher than areas without a large amount of PM 2.5: “counties [in the United States] that average just one microgram per cubic meter more PM 2.5 in the air had a COVID-19 death rate that was 15 percent higher”(Pollution Made COVID-19 Worse. Now Lockdowns Are Cleaning the Air). Fine air pollution particles that get inside of the human body also cause things like heart disease, hypertension, diabetes, and having trouble breathing while also weakening the immune system and lungs. These factors contribute to the direct correlation between deaths from COVID-19 and air pollution. Pollution has also declined dramatically during the COVID-19 lockdown. However, this decline in population will probably be short lived, and the amount of pollution might even get worse after most countries are out of lockdown. Hopefully, the COVID-19 pandemic will change people's mindset about pollution and help them realize that air pollution and other kinds of pollution can be controlled.

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This article talks about how the Corona virus is similar in some ways to the influenza pandemic. It states that this outbreak of COVID-19 has the potential to be as bad as the 1918 influenza outbreak which infected one third of the people on earth. As urbanization has increased nowadays it is likely to spread quicker.

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I learned how the safety measures that were taken during the 1918 influenza pandemic were similar to the ones taken now. For example, people had to social distance and quarantine and how in some cities people had to wear masks in public. I also found interesting that the police were given permission to arrest anyone in Chicago who was seen not covering their face while sneezing.

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I learned that even if there is a little bit more air pollution in a specific area Covid-19 death rates are normally much higher. While Covid-19 is much more lethal due to the levels of air pollution currently, air pollution is declining due to people staying at home and quarantining.

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I learned that during the influenza outbreak in 1918, there was racial prejudice, similar to the prejudice around COVID-19. Governments are implementing similar social distancing policies to the policies that were in place in the 1918 pandemic.

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I learned about how pollution makes the symptoms and chances of getting COVID - 19 worse but how the pandemic has caused the air to be cleaner.

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I learned all about how pollution increases the chances of getting Covid-19 and the  effects  of  the symptoms. Now that everyone is in  lockdown the  air is much cleaner  and  nicer outside.  New York's pollution rates has gone down 22% and Los angeles  down 33%. These cities usually have a lot of traffic  and with the less cars pollution rates have dropped a lot.

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I learned a lot about the similarities between the 1918 influenza and covid 19. I also learned that they are going to try to use some of the strategies they used back then with covid.