COVID-19 & Cities: Pollution and the Environment

By: Carly Berke

On Wednesday, May 13th, 2020, the Initiative on Cities (IOC) hosted a discussion on the impact of COVID-19 on pollution and urban air quality as part of our ongoing COVID-19 & Cities series (click here to watch the webinar). David Miller, Director of International Diplomacy at the C40 Cities Climate Leadership Group and former Mayor of Toronto (2003-2010) and Lucy Hutyra, Associate Professor of Earth and Environment at Boston University, participated in the panel to offer their insight into both the scientific understanding and policy implications of improved urban air quality during COVID-19.

“It seems perverse to talk about what you might call the ‘good side’ [of COVID-19]: That the shut down has led to a temporary decline in air pollution,” opened IOC Director Graham Wilson. But “COVID-19 is reinforced by pollution problems. People living in bad environmental circumstances are more vulnerable to getting and dying from COVID-19 than people who are in better environmental circumstances.”

Hutyra began the discussion by breaking down air pollution from a scientific perspective, explaining the factors that increase or decrease the atmospheric concentrations of significant air pollutants.

Several compounds contribute to air quality. The most visible pollutant captured by images is nitrogen dioxide (NO2), a short-lived air pollutant associated with the combustion of oil, gas, and coal. White Hutyra admitted that nitrogen dioxide concentrations have decreased, leading to less air pollution, percentages vary by city; estimates from TROPOMI, the tropospheric monitoring instrument, suggest that nitrogen dioxide concentrations are down 43% in Wuhan, down 38% in Milan, down 21% in Washington, D.C, but are showing no change in Iran. 

Hutyra warned that levels in areas seeing reductions will begin to increase again as cities begin to open back up, and that these declines are not entirely due to COVID-19 related effects. Nitrogen dioxide exists for only a few hours and declining levels usually indicate a local change in atmospheric conditions. “When we think about how these gases are changing and how the air quality is changing, it’s important to note that COVID is not happening in isolation,” said Hutyra. “Would these concentrations have gone down anyway with the seasonal cycle?”

Hutyra is referencing declines in nitrogen dioxide concentrations that we typically see from January through May due to solar angles and cloud cover. She warned we cannot immediately attribute current changes in atmospheric nitrogen oxide concentration to COVID-19, as we would be seeing these declines irrespective of the global pandemic. 

In addition to nitrogen dioxide, particulate matter (PM) has also decreased, which might actually lead to some short-term warming, because more PM reduces how much radiation and sunlight reaches Earth’s surface. Lastly, Hutyra referenced ozone (O3). There has been an increase in ozone concentration because of decreased levels of nitrogen dioxide. Most cities are reporting an increase of ozone by a factor of 1.5–2, which is important, because ozone is a significant pollutant that is regulated by the Environmental Protection Agency (EPA) and has been linked to pulmonary and heart disease.

Hutyra then turned to carbon dioxide (CO2), the gas most widely known as a primary culprit causing global warming and climate change. Hutyra referenced her own working measuring the carbon dioxide concentration in Boston’s atmosphere, which she conducts on the roof of the Boston University College of Arts & Sciences (CAS). Right now, we’re seeing a decrease in carbon dioxide concentration in Boston by about 12 parts per million, but Hutyra emphasized that this difference is relatively small and cannot be accounted exclusively to COVID-19. In fact, measuring the comparing carbon dioxide reduction trends from the past few months to the same months from 2019 shows they are almost identical, decreasing by relatively similar levels. This is a reflection that current carbon dioxide measurements are an indication of seasonal changes rather than emissions reductions due to COVID-19.

“The differences we’re seeing with these massive changes in the economy are not very clearly visible in the urban atmosphere, in the case of carbon dioxide,” said Hutyra. “It is not because Boston is somehow different from other cities.”

Hutyra provided a graphic that depicted Boston’s seasonal emissions profile, in which residential emissions are higher in the winter largely because of heating; in the summer, the lack of heating causes transportation emissions to become a higher percentage of total emissions. Emissions also tend to dip in the spring because trees begin to absorb more carbon dioxide as their leaves grow back. As a result, it is not entirely possible to establish a direct and concrete correlation between the COVID-19 shutdown and emissions reductions.

Thinking globally, however, Hutyra referenced a recent Carbon Brief report, which suggests global carbon emissions will fall by 6–8% in 2020, the largest decline in carbon dioxide emissions we’ve observed in modern day history. “This is good; we need to reduce CO2 emissions,” said Hutyra. “But this is not a good way to do it.”

Moreover, the current estimated emissions reductions are only a small proportion of what’s needed to meet the threshold set by the Paris Climate Agreement. To limit global warming to below 1.5°C pre-industrial levels by 2050, we need to cut global emissions by 7.6% every year this decade.

In 2020, a global pandemic and massive economic shutdown have somehow gotten us there, but evidently, COVID-19 is not a sustainable emissions reductions solution. Hutyra urged that committing to adequate emissions reductions solutions means redefining how we move and work in cities. Moving forward, cities will have to think more critically about what remote work looks like and how city residents are going to get around, hopefully more often by bike or walking in line with new 15-minute city models. And while air quality has improved in the short term due to reduced emissions and combustion, there is concern surrounding long term policies that roll back environmental regulations to help manufacturing and industry make up for lost production. Environmental regulations that are under threat of being rolled back pertain specifically to air quality, and how they are implemented could create serious long term environmental consequences. 

Next, Miller spoke about the policy implications of COVID-19’s impact on air quality and offered his perspective “through the lens of a practitioner who is helping cities make [the] right decisions on air quality.”

C40 is a coalition of 94 mayors from the world’s largest cities, and its members represent a total of 700 million people. The group is comprised of cities with populations over three million or cities taking significant climate action that have committed to peaking greenhouse gas emissions in 2020, halving them by 2030, and reaching net-zero by 2050. Thus far, 34 cities in C40 have peaked their emissions this year.

Air quality and its relationship to COVID-19 is a pertinent issue to Miller and C40. It is a topic of active research that seeks to determine, among other linkages, the potential for air pollution to worsen the pandemic’s effects on health, changes in pollution during the shutdown period, and policy and public communication considerations during the pandemic to maintain low carbon emissions levels.

Miller argued that public health issues have always been closely linked to air quality and that it continues to be an ongoing concern for mayors. Low-income and marginalized neighborhoods in large global cities tend to experience worse health outcomes as a result of air pollution, creating a direct linkage between air quality, health, and equity, as Miller demonstrated. As a result, city climate action should also target public health and equity. What’s more, mayors are finding you can speak to people about air quality and local health in a way that you sometimes not about climate change, because air quality is more immediate, short-term, and visible. 

Miller explained that we know those with preexisting health conditions are at increased risk of severe health outcomes or death from COVID-19. There has already been decades of research demonstrating that exposure to air pollution damages the heart and lungs, as well as research on similar viral infections to COVID-19 that have shown relationships between air pollution exposure and increased risk of death from infections.

One the other hand, several items need more research and evaluation, like the relationship between COVID-19 mortality and air pollution. While research is ongoing, Miller cautioned the use of non-peer reviewed studies for policymaking, while recognizing that it can be warranted until further research is available. “Confirming these relationships to the current pandemic will be an important but significant evidence on the harm of air pollution already exists,” said Miller. “From a mayor’s perspective, you sometimes need to act on incomplete evidence and the best kind of evidence you can get.”

C40’s Air Quality Network, which helps cities develop and implement air quality policies and solutions in support of efforts to measure, understand, and reduce air pollution to improve public health and meet climate goals, is one of 17 within C40 that provide resources, knowledge, and insight to mayors on important issues and establishes communication lines between multiple cities. The Air Quality Network has historically worked on valuation of air pollution trends and has used analytic methods to assess changes in air pollution. This includes looking at what local sources contribute to emissions, like if a city heavily relies on automobile transit. 

The Air Quality network is collaborating with cities that are already taking action on addressing COVID-19 through climate and emissions reduction strategies. Examples include Mexico City and Barcelona, which are collaborating on communicating the complexity of ozone increase during lockdown, as well as London, Paris, Madrid, and Milan, which are analyzing and assessing the results of vehicle restriction schemes. Such schemes include ultra low emissions zones, in which vehicles that significantly pollute the environment are charged a high fee to drive in the zone. Paris is also creating 650 km of cycling routes in an effort to integrate the 15-minute city model. Bogotá, Lima, and others have been expanding walking and cycling to create space and prepare for the transition, and Milan is prepared to release plans on reallocating space to walking and cycling. 

Several regions in the UK and North America have also issued guidance and raised awareness on the health impacts of open fire or wood burning stoves to protect citizen’s health. For example, Vancouver has issued a ban on open burning to reduce air pollution during the pandemic.

Another critical area that mayors are rethinking is transportation, because several large cities do not function without excellent public transport systems. The challenge now, however, is making public transit safe and efficient in a world that continues to practice physical and social distancing.

Personally, Miller hopes to see cities prioritize the safety of public transit workers and operators, cleaning and sanitation, and frequency of transit options. “If you align that support for public transport with significant increases in the ability for people to get around through active transport—cycling and walking and repurposing roads for that—you have a chance for allowing these cities to function. If policy decisions are taken from state and national governments that don’t provide enough funding to support public transport, you return to automobiles and cities cannot function from economic, traffic, and air quality and health problems.”

It’s a daunting challenge, Miller admitted, but COVID-19 has revealed that remote work feels more possible now, and more lifestyle changes are to come, including a shift from reliance on fossil fuels to more sustainable resources.

Above all, Miller emphasized cities need to target recovery investment so that they also address equity in a way that brings jobs back while setting cities up to be low-carbon. “It’s abundantly clear if we make the right decision now—particularly if national and state governments’ investments think consciously about low polluting, low carbon, high air quality, and an equitable future— this is a moment that can be transformative. But that will only happen politically if there is excellent science on which to base it that is communicated clearly and simply.”