TL;DR — The COVID-19 pandemic monumentally impacted human health around the globe, but it also had impacts on air quality and the consequences of air pollution exposure. During the initial lockdowns in 2020, air quality in many places experienced temporary improvements, but research revealed that environmental justice communities and other underresourced neighborhoods — which often experienced the largest improvements — still suffered from worse air quality compared to higher-income and more white communities. Additional research demonstrates that air pollution exposure in these communities was linked to more severe health outcomes and higher morbidity and mortality due to COVID-19, driving home the need to encompass environmental justice considerations within policy to mitigate these impacts.

How the COVID-19 pandemic impacted the air pollution landscape

The COVID-19 pandemic has had well-known impacts on air pollution levels, which were first and most notably seen during the initial lockdown that took place in March and April 2020.

During this lockdown period, cities across the globe saw significant decreases in air pollutant levels — especially in NO2, particulate matter, and carbon dioxide fossil fuel emissions — particularly due to decreased road transport and the slowing of other human activities that typically produce air pollution.

According to one study, this period saw an average 60% reduction in NO2 levels and a 31% reduction in fine particulate matter levels across 34 countries as compared to previous years, even after weather conditions were controlled for.

The figure above demonstrates the air quality improvements seen over the initial lockdown period in spring 2020 in four cities across the globe, all with sizable reductions in NO2 pollution levels. (Image source: Statista)

To learn more about how the pandemic impacted air quality as a whole and how 2020 served as a global laboratory for air pollution research, read our blog here.

We also know that the COVID-19 pandemic did not affect people or regions equally; instead, it reproduced existing patterns of inequality that disproportionately affect people of color and low-income people.

How the COVID-19 pandemic led to disparities in air pollution exposure and reduction

It is known that communities of color, low-income communities, and other marginalized groups tend to face disproportionately high levels of air pollution. However, it can be difficult to disentangle the various factors at play that lead to this outcome.

A study by Bluhm et al. published in Nature helps to elucidate this phenomenon by estimating the disparities in air pollution exposure experienced by different communities during the shelter-in-place orders in California in 2020. 

The researchers found that the shutdown and its associated temporary improvements in air quality led to disproportionate reductions in air pollution exposure for non-white (especially Hispanic and Asian) individuals and low-income people

A study by Kerr et al. builds upon this research, finding that despite significant temporary reductions in air pollution during the beginning of the lockdown period, communities of color often continued to experience disproportionately high levels of air pollution in their neighborhoods. The researchers state that decreases in air pollution during this period — especially the decreases in passenger vehicle traffic that led to lower NO2 levels in urban areas — were insufficient to eliminate the existing disparities that cause environmental injustice. 

That is, a number of underresourced neighborhoods in their study continued to experience NO2 levels that were up to 50% higher than the pre-pandemic NO2 levels of nearby highest-income, majority-white neighborhoods.

The least White communities experienced the largest NO2 reductions during lockdowns; however, disparities between the least and most White communities are so large that the least White communities still faced higher NO2 levels during lockdowns than the most White communities experienced prior to lockdowns, despite a ∼50% reduction in passenger vehicle traffic.”

— Kerr et al.

The study also looks at specific drops in air pollution in New York, Atlanta, and Detroit and links decreases in neighborhoods of color with other existing contributors to environmental justice inequalities, like the existence of major highways and industrial facilities in these neighborhoods. 

The researchers linked the biggest drops in nitrogen dioxide pollution during COVID-19 shutdowns to a community’s proximity to highways and interstates. Marginalized urban areas are also more likely to be located near interstates…where traffic is responsible for a large portion of urban nitrogen dioxide pollution and other forms of pollution.” 

— Kerr et al.

The disparate health outcomes during the pandemic due to air pollution exposure

The COVID-19 pandemic also impacted human health disproportionately. According to 2020 data, counties with a high proportion of African American residents had six times the death rate than more white counties, showing clear racial disparities in pandemic outcomes.

In relation to air pollution, research finds that higher pollution exposure was linked to an increased risk of contracting COVID, admittance to the ICU, and death due to COVID.

Hospitalized COVID-19 patients who had been chronically exposed in their neighborhoods to higher particulate matter—such as smoke, soot, and dirt—had increased risks for admission to the intensive care unit (ICU) and death compared to those without such exposure”

— Bozack et al.

Researchers Petroni et al. found that exposure to hazardous air pollutants, such as formaldehyde, asbestos, and mercury was linked to a 9% increase in the risk of death in patients with COVID

Essentially, the higher the air pollution index, the more it correlated to poor health outcomes due to COVID-19. The likely reason: these pollutants cause respiratory stress, thereby increasing vulnerability to severe illness from COVID-19.”

— American Lung Association

In a retrospective analysis of an ethnically diverse sample of patients with COVID-19 in New York City, researchers found that there was an 11% higher risk of mortality and 13% higher risk of admission to the ICU associated with chronic exposure to particulate matter air pollution, even for PM levels that do not exceed regulatory guidelines.

Research out of Mount Sinai concurs with these findings that even pollutant concentrations below the US EPA regulatory standards are associated with increased morbidity and mortality among hospitalized COVID patients — driving home the point that there is truly no safe level of air pollution. This reminds us of the importance of reducing air pollution as a public health factor, especially in neighborhoods that are disproportionately affected by these detrimental health outcomes.

Recent research has also honed in on the impacts of exposure to specific harmful air pollutants. 

Particulate matter — a pollutant well-known to have significant negative effects — has been linked to an 11% increase in the COVID-19 death rate for just a 1 microgram per cubic meter increase in long-term exposure. Research from Harvard connects this to racial disparities, finding that counties with higher PM pollution and a higher number of Black residents also had a 49% increase in the COVID death rate.

Read our air quality measurements series blog here for more information on the effects of particulate matter air pollution.

Nitrogen dioxide has also been connected to COVID outcomes.

According to the study, a 4.6 parts per billion increase of nitrogen dioxide in the air was associated with 11.3% and 16.2% increases in COVID-19 case-fatality and mortality rate, respectively. The researchers argue that a 4.6 parts per billion reduction in long-term exposure to nitrogen dioxide would have prevented over 14,000 COVID-19 deaths among those who tested positive for the virus.”

— American Lung Association

Many studies examining the relationship between COVID, air pollution, and racial disparities have been conducted in economically developed countries, but similar relationships have also been found in economically developing countries. 

One study looking at four different countries in Latin America found that an increase of one microgram per cubic meter in fine particulate matter pollution was linked to a 2.7% increase in the COVID mortality rate. The researchers noted that this relationship was most prominent in urban areas, which tend to have pollution in excess of air quality guidelines. 

The lessons we’ve learned

The COVID-19 pandemic and its ties to air quality and environmental justice have taught us many valuable lessons that we take forward in the fight for cleaner air.

This situation speaks to the degree to which low-income neighborhoods and communities of color continue to bear the brunt of air pollution exposure and its negative impacts as well as the degree to which environmental racism must be addressed in the work to improve air quality.

Forward-looking research findings also help to highlight potential policy changes to address these disparities. 

A 2021 George Washington University notes that policies to reduce traffic-related emissions may not be enough to mitigate the pollution disparities experienced by underresourced neighborhoods. Policies must also focus on the inequalities that exist due to structural, systemic, and environmental racism in these underserved neighborhoods — such as the effects of heavy-duty trucking and industrial facilities — in addition to addressing overall emission levels.

The pandemic and its relation to air pollution also reiterate the fact that there is no safe level of air pollution, as increases in the risk of negative outcomes from COVID-19 were found even in conditions where air pollution levels did not exceed regulatory guidelines. This also serves as a reminder that even in places where air pollution is relatively controlled, underresourced populations are still disproportionately suffering from these negative outcomes, especially when it comes to their health.

Interested in measuring air quality for cleaner air, improved physical and mental health, and a healthier climate? Get in touch with our team to learn more about our Sensing-as-a-Service solution for governments, businesses, and community organizations, using our Clarity Node-S monitors and modules that do not depend on infrastructure like WiFi or power — making them especially resilient during environmental disasters.