Long Concerned About Air Pollution, Baltimore Experienced Elevated Levels on 43 Days in 2020

While a new national study found that a majority of Americans faced a similar threat level, one Maryland activist says it’s “still worse than we should tolerate.”

Southbound Interstate 95 is seen in Baltimore, Maryland on March 22, 2017. Credit: Jonathan Newton/The Washington Post via Getty Images
Southbound Interstate 95 is seen in Baltimore, Maryland on March 22, 2017. Credit: Jonathan Newton/The Washington Post via Getty Images

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The air in Baltimore isn’t as toxic as it once was—in 2005 it had the worst air pollution mortality rate among the 20 most populated cities in the country. But still, residents and activists continue fighting to reduce pollution. Many of their efforts are directed toward Wheelabrator, one of more than 70 trash incinerators in the country. But there’s also the issue of traffic emissions, a greater source of air pollution in the area. 

Last year in Baltimore, there were 43 days with elevated levels of air pollution. This hazard, the “greatest environmental health risk factor in the United States,” according to a new report based on federal government data, is tied to 100,000 to 200,000 deaths nationally per year.

The report, “Trouble in the Air,” examined air pollution levels around the country. It found that more than 70 percent of the U.S. population—237.6 million people—experienced longer than a month of elevated air pollution in 2020. Elevated was defined as exceeding levels that the Environmental Protection Agency considers “good.”

But the “Environmental Protection Agency hasn’t updated our federal air quality standards in years, and many organizations say they’re not protective enough of human health,” said Morgan Folger, a clean car campaign director for Environment America, a federation of environmental advocacy groups that contributed to the study.

Researchers looked specifically at two different kinds of pollutants that are associated with a slew of cardiovascular and respiratory problems: ozone, the main ingredient in smog, and PM 2.5, or particulate matter measuring roughly one-thirtieth of the width of a human hair or smaller.


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This report comes two weeks after the World Health Organization released new guidelines for air pollution, which included updated standards for ozone and PM 2.5 for the first time since 2005. Folger noted that the United States’s air quality standards still lag behind the WHO’s 2005 benchmarks. However, there is currently no evidence to suggest that there is any safe level of air pollution.

The Baltimore area, which researchers combined with suburban Columbia and Towson, was one of the hundreds of places analyzed in “Trouble in the Air.” It fared far better than many other densely populated locales, such as San Diego, which experienced 232 days of elevated pollution levels in 2020. Two other Californian cities rounded out the top three for the most populated places with the worst air—Los Angeles and Riverside.

Emily Scarr, state director of Maryland PIRG, a public interest advocacy group that also contributed to the report, said that for those who are in closer proximity to forest fires on the West Coast, concerns about air quality are at the front of mind. 

“It’s not bad enough to get people’s attention,” Scarr said about air quality in Baltimore, “but still worse than we should tolerate.”

Air pollution contributes to asthma, cancer, chronic obstructive pulmonary disease (COPD), stroke and cognitive decline, among other maladies. It has also been shown to decrease fertility and academic performance. Furthermore, children are generally more susceptible to air pollution because they are still developing and spend a greater amount of time outdoors than adults.

“I monitor, I look at my weather app [for pollution levels] in the summer, before I take my kids to a playground to decide if I’m going to go outside. So that in itself is alarming to me,” said Scarr.

Air Pollution and Covid-19

The improvement in Baltimore’s air quality over the last 30 years is primarily attributed to more stringent state and federal emissions regulations and targeted policies, including the Maryland Healthy Air Act, which focused on power plants.

In Baltimore, the single largest stationary source of air pollution is the Wheelabrator trash incinerator visible from I-95. Its emissions include nitrogen oxides and volatile organic compounds, which combine to create ozone when exposed to sunlight, a process accelerated by heat.

While pollution from Wheelabrator exacerbates health problems like asthma, it likely doesn’t compare with the effects of traffic pollution; in 2017, 74 percent of nitrogen oxide emissions in Maryland came from transportation, far exceeding the national average of 59 percent, according to the report.

In addition to ozone precursors, Wheelabrator emits PM 2.5. Particulate matter can take a solid or liquid form, and it usually forms in the air, like with ozone. But in the instance of Wheelabrator, it rises from the smokestacks fully formed. In either case, its size allows it to enter the human body and penetrate deep into the lungs. Additionally, those particles can travel hundreds of miles.

“Air pollution does not respect our arbitrary lines between cities or states,” Folger said.

According to a report from the Maryland Department of the Environment, “Up to 70% of ozone and fine particle air pollution in Maryland originates in an upwind state.”

Recent research from Harvard University has found that populations in areas with long legacies of particulate matter pollution have higher Covid-19 mortality rates, which has made efforts by environmental justice groups to shut down incinerators and other polluting facilities even more urgent.

Late last year, Wheelabrator’s contract was extended for another decade, to last through 2031. In order to continue operating, it’s required to install about $40 million worth of emissions upgrades.

In August, the University of Maryland held its seventh annual Environmental Justice and Health Disparities Symposium. During a panel discussion on air pollution, experts discussed the promise of hyper-local air monitors.

“It’s a wonderful tool to build partnerships with communities,” said George Aburn, the director of air and radiation at the Maryland Department of Environment. “It’s sort of a citizen-science approach. … It allows for us, the state, to provide a useful function to the citizens.”

“Trouble in the Air” researchers said that their nationwide analysis is likely an undercount of the real number of days with elevated air pollution because of data gaps. The increasing number of community-specific air monitors around the country could help address the problem of insufficient data.

Funding for these monitors would be provided by Sen. Ed Markey’s (D-Mass.) “Environmental Justice Air Quality Monitoring Act” introduced in July. If passed, it would authorize “$100 million annually to establish a five-year pilot program for hyperlocal air quality monitoring projects in environmental justice communities,” a press release from Markey’s office said.

Air Pollution and Climate Change

The recent nationwide report also explained how pollution and climate change have entered into a feedback loop with one another. 

“Higher temperatures have already resulted in increased ozone, despite lower emissions of the chemicals that create ozone,” the report said. Higher average temperatures also make extreme heat events more likely, such as bigger and longer-lasting forest fires that spread PM 2.5 and the precursors to ozone. Furthermore, areas susceptible to drought, such as the southwestern United States, are likely to see even less rain in the future because of climate change. This will exacerbate the dry, dusty conditions that spread particulate matter.

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Increasing ozone will also damage the ability of plants to sequester carbon from the atmosphere. As wildfires continue to rage with greater intensity and frequency, the PM 2.5 they emit will create a warming effect. 

“Electrification to me is a public health intervention,” said Dr. Sacoby Wilson, an associate professor at the University of Maryland’s School of Public Health, who moderated the panel on air quality. His statement summed up the recommendations put forward by the authors of “Trouble in the Air,” who said renewable energy is needed to halt the interplay between pollution and climate change.

“We’ve known that cars are toxic for a long time, but we haven’t made enough progress to move towards electric vehicles,” Scarr said. “It’s a political problem, right? It’s not something that can be solved by individuals changing their behavior. So ideally, our federal government would be the one who could make the biggest difference in transportation policy.”

“Transportation in and out of the city is commuters, it’s large trucks,” she said. “It’s not controlled just by the mayor himself.”