By Tyler Haughn
Sometimes it’s what you can’t see that is the most dangerous.
Each time Somerville resident Ellin Reisner steps out onto her front porch during rush hour, her view is always the same. She has a clear image of the sprawling concrete walls of Interstate 93, located nearly 500 meters from her home.
It is dominated by a cacophony of traffic sounds. Reisner and her neighbors have learned how to cope with the constant honking but are more concerned by a looming, invisible threat: ultrafine particles.
These nanosized particles are invisible to the naked human eye but they can cause severe health problems. They can usually be traced to automobiles and airplanes, meaning people who live close to major roadways are usually exposed to a higher concentration of these dangerous particles.
This has led many Somerville residents who live near Interstate 93 to become increasingly concerned by their exposure levels.
“I’m close enough to be concerned about the pollution,” Reisner said. “I’m very concerned about it for my neighbors, who are much closer to the highway. I don’t even open my windows that face the highway during peak hours of traffic.”
Somerville is New England’s most densely populated city, accommodating more than 75,000 people across 4.1 square miles. It is home to several highways that commuters use to travel to Boston or neighboring Cambridge for work. Interstate 93 spans around 190 miles through Massachusetts, New Hampshire and Vermont, bisecting the northeastern parts of the city.
Interstate 93 was originally constructed in 1973. This process led to the demolition of a neighborhood and business district in east Somerville. Property values quickly dropped as a result of the increased traffic. The state promised to build noise barriers to help nearby residents reduce the commotion. It never happened.
Somerville has experienced some of the highest rates of lung cancer and heart attack deaths in Massachusetts throughout the last decade. Researchers have linked this to air pollution caused by busy roadways.
These disproportionate mortality and morbidity rates led Reisner and other concerned residents to renew their interest in getting to the bottom of Somerville’s air pollution problems.
“There was really no explanation,” Reisner said. “When you look at Cambridge, which is right next to Somerville, there they had below normal rates of cardiac disease and lung cancer. But Chelsea and Somerville, in particular, had the highest.”
Reisner first reached out to air pollution expert Doug Brugge 15 years ago to see if he would be interested in working together to learn more about pollution in Somerville along Interstate 93. Brugge was working as the director of the Tufts Community Research Center at the time.
This led to the creation of the CAFEH partnership, which now serves as a platform to support multiple air pollution studies. These projects feature a dynamic collaboration between community partners and academics from local educational institutions, namely Tufts.
“We thought we needed to study the air pollution problem because we felt that highway pollution was a very serious issue,” Reisner said.
Reisner serves as the president of the Somerville Transportation Equity Partnership (STEP), which has been collaborating with CAFEH studies alongside other community stakeholders since 2006. STEP was formed four years earlier and its first major project involved advocating for the Green Line extension in Somerville to make public transportation more accessible.
Today, the organization focuses on advancing sustainable land use through regional transportation issues.
Interest from community members like Ellin Reisner influenced Brugge and his colleagues to conduct studies and develop practical evidence-based solutions. Brugge attributes this to the input community members have provided throughout the project so far.
“It evolved very quickly into doing something about it,” Brugge, director of the CAFEH studies, said. “I think that’s a function of it being a community collaboration because the community is not very interested in being studied indefinitely. The community would, even with limited evidence about their risk, want you to do something to reduce the risk.”
Brugge said an estimated 200,000 vehicles travel through the Interstate 93 extension in Somerville every day. The neighborhoods located nearby must contend with large amounts of air and noise pollution because of the constant buzz of commuter traffic. The pollution also contributes to smog and negatively affects air quality.
These same locations are also home to some of Somerville’s most vulnerable and disenfranchised communities. A CAFEH report highlights that many residential neighborhoods near Interstate 93 are known as Environmental Justice communities, meaning the residents are more likely to be exposed to higher pollution levels.
The communities are, on average, less affluent and less educated than their neighbors. Furthermore, these neighborhoods are also home to a large number of non-English speakers and are more racially diverse than in other parts of Somerville.
The CAFEH studies have played a key role in uncovering how the ultrafine particulate matter caused by automobile traffic has led to increases in asthma and cardiovascular disease within east Somerville.
There is a growing concern among scientists about the excessively high levels of ultrafine particles residents who live next to the busy roadway are exposed to. Ultrafine particles are less understood and are not currently regulated by the Environmental Protection Agency. This is is despite growing warnings from scientists.
“Ultrafines are higher near the highway, they change rather rapidly with rush hour with changes in wind speed or wind direction,” Brugge said. “Who is exposed to high levels of ultrafine can be different than who’s exposed to the regulated particulate matter.”
Brugge says the EPA does not accept that the contemporary health literature is conclusive enough to determine that ultrafines can be linked with health outcomes.
Ultrafines have been found to cause serious health concerns. They can penetrate the lungs, travel throughout the body and even affect the brain.
“I think there’s enough evidence that we should be concerned about them,” Brugge said. “They have an ability to translocate across biological barriers that larger particles would not be able to cross. That is one of the reasons we’re particularly concerned about ultrafine particles.”
The EPA regulates other inhalable particles instead.
Particulate matter (PM) consists of extremely tiny particles found in the air. PM 2.5 is the most dangerous variety and is smaller than a single human hair, measuring 2.5 micrometers in diameter. PM 2.5 is regulated at both the state and federal levels.
Jonathan Levy, a professor of environmental health at the Boston University school of public health, said air quality across Massachusetts has been gradually improving over the past two decades. A major challenge is finding ways to confront the pollution caused by the large number of major highways that flow in and out of the Greater Boston area. Levy contributed to the CAFEH study alongside Brugge and Reisner.
“As the science moves, we’ve regulated precise size fractions,” Levy said. “I think the next big question is if there will be a future move away from PM 2.5 to something else.”