When It Comes to Your Health, Location Matters

A man and woman standing in front of a bookcase.
Jonathan I. Levy, Sc.D.(l), and Francine Laden, Sc.D. (r)
A study in Massachusetts has found that concentrations of two air pollutants, nitrogen dioxide and fine particulate matter, decreased significantly between 2003 and 2010, but African Americans and Hispanics living in the city continued to be exposed to a greater share of the pollutants than other racial and ethnic groups were. While African Americans and Hispanics had the greatest exposure to the pollutants, low-income families, and those with less education were also more likely to live in areas of higher exposure.

“The good news is that air quality now is much better than it was 10 years ago,” said Jonathan I. Levy, Sc.D., of the Boston University School of Public Health, who is one of the authors of the study. “But we have not closed the gap among some of the racial, ethnic, and low–socioeconomic status populations. In fact, the inequities are greater in some settings.”

The two pollutants—particularly fine particulate matter—are associated with poor health outcomes, Levy said. Previous research has shown that exposure to these pollutants is associated with negative outcomes, including an increased risk of asthma, respiratory infections, low birth weight, autism spectrum disorder, and death.

The study, “Temporal trends in air pollution exposure inequality in Massachusetts,” was funded by the National Institute on Minority Health and Health Disparities (NIMHD), the National Institute of Environmental Health Sciences (NIEHS), and the Environmental Protection Agency (EPA). The data for fine particulates was from 2003–2010. The nitrogen dioxide data was from 2005–2010.

Mapping Health Disparities

The study used existing data to model the amount of pollution in particular areas over an 8-year period. The researchers used U.S. Census and other demographic data to determine which populations lived in the areas during that time.

Fine particulate matter, which can be emitted directly or formed from gases emanating from sources such as power plants, tends to spread over larger regions. Nitrogen dioxide, which emanates mainly from traffic, can concentrate in smaller areas and have greater spatial variation. The study found that exposure inequalities were much greater for nitrogen dioxide than for fine particulates. The study is descriptive and does not explain why these disparities exist.

“Figuring out the precise drivers of environmental health disparities is challenging, other than to note that if you don’t have residential segregation, you cannot have racial disparities in exposure to outdoor air pollution,” Levy said.

Part of a Larger Effort

The study is part of a larger effort of the Center for Research on Environmental and Social Stressors in Housing Across the Life Course (CRESSH), a partnership between the Boston University School of Public Health and the Harvard T.H. Chan School of Public Health. CRESSH studies differences in pollution and health outcomes in communities in Massachusetts and the drivers of these differences. The studies involve a range of scientific disciplines and involve a strong community engagement component. Levy and Francine Laden, Sc.D., of the Harvard T.H. Chan School of Public Health, lead CRESSH.

“We know that air pollutants are related to health outcomes such as cardiovascular mortality,” Laden said. “What CRESSH adds to that is an analysis of the disparities among different populations.”

CRESSH is made up of three research projects, along with an administrative core, a community engagement core, and a pilot project program.

  • The Health Effects Across the Life course (HEAL) research project examines the association between pollutants and health outcomes across the lifespan and how the association can be modified by non-chemical stressors and social determinants.
  • The Home-based Observation and Monitoring Exposure (HOME) project measures the environment inside the home, including pollutants, indoor temperature, noise, and ventilation, to determine factors that explain between-household variability in exposure.
  • The Mapping Spatial Patterns in Environmental Health Disparities (MAP-EHD) project is developing a large database to describe disparities in exposure to chemical and non-chemical stressors across Massachusetts, ultimately modeling the health benefits of interventions to reduce exposures. The study showing continuing disparities in exposure to fine particulates and nitrogen dioxide is from the MAP-EHD project.

Housing is an area of emphasis for CRESSH because so much of an individual’s time is spent indoors and because the environment inside the home can be more readily controlled by individuals and addressed by local policy measures.

Taking It to the Streets

CRESSH studies are now looking at how housing conditions such as differences in ventilation, “leakiness,” and the presence of smokers in the home can affect health and health disparities. If some of the exposure disparities are housing related, the next step is to find interventions to reduce them.

Laden said that the projects engage community residents to help ensure that the team produces findings and practical next steps that community members can use. Community members can also help the researchers disseminate findings to individual participants and to the community as a whole.

“We want something solution-oriented where we could say, ‘If you take this step, here is how it changes your exposure and here are the health implications,’” Laden said.

CRESSH is one of the five Centers of Excellence on Environmental Health Disparities Research conducting environmental health disparity studies across the United States. NIMHD, NIEHS, and EPA are funding the Centers.


  1. Rosofsky, A., Levy, J. I., Zanobetti, A., Janulewicz, P., & Fabian, M. P. (2018). Temporal trends in air pollution exposure inequality in Massachusetts. Environmental Research, 161, 76-86.

Posted March 7, 2018