For individuals traveling through the Bronx at various times, exposure levels to particulate matter measuring 2.5 microns or larger increase by approximately 2.4 percent when considering daily travel behaviors, according to recent research.
A new study co-authored by MIT researchers highlights noteworthy disparities in people’s exposure to air pollution by factoring in their daily mobility.
Conducted in the Bronx, New York, this research goes beyond merely estimating air pollution exposure based on residential or workplace locations. It utilizes mobility data to analyze individuals’ movements throughout a typical day, offering a comprehensive evaluation of how the environment affects them.
The findings indicate that when daily travel patterns are taken into account, exposure to particulate matter 2.5 microns or larger increases by about 2.4 percent.
“A key advantage of our study is our effort to enhance the quality of information on air quality and to gain more detailed insights into people’s mobility,” explains Paolo Santi, a principal research scientist at MIT’s Senseable City Lab and co-author of the paper presenting the study’s findings. “This allows us to map people’s movement trajectories, making this the first instance where we could merge these data to create a new exposure metric.”
After all, daily pollution exposure for individuals is often a complicated mix of living, working, or traveling near sources of particulate matter.
“As people navigate the city for jobs, education, and various activities, studying this movement helps us obtain improved exposure data,” adds An Wang from Hong Kong Polytechnic University, another co-author of the study.
The research paper titled “Big mobility data reveals hyperlocal air pollution exposure disparities” will be published in Nature Cities.
The study’s authors include Iacopo Testi from the Senseable City Lab, An Wang from Hong Kong Polytechnic University, Sanjana Paul, a graduate student in DUSP, Simone Mora from the Senseable City Lab, Erica Walker, an associate professor at Brown University School of Public Health, Marguerite Nyhan, a senior lecturer/associate professor at National University of Ireland, University College Cork, Fábio Duarte from the Senseable City Lab, Santi, and Carlo Ratti, who directs the Senseable City Lab.
To carry out the study, researchers equipped New York City’s civic service vehicles operating in the Bronx with solar-powered environmental sensors, including optical particle counters, temperature, humidity sensors, and GPS devices.
“This approach demonstrates that cities can repurpose their existing vehicle fleets as environmental sensors,” remarks Mora.
To analyze how pollution exposure varies for people traveling through the Bronx at different times, the researchers utilized anonymized phone records from 500,000 individuals, resulting in around 500 million daily location data points from New York.
Data on ground-level pollution revealed that the southeastern Bronx, where expressways and intense industrial activity converge, experiences the highest levels of particulate matter.
The mobility data also uncovered disparities in exposure linked to demographics, showing existing income gaps and notably larger disparities by ethnicity. For example, predominantly Hispanic neighborhoods face some of the highest exposure rates, yet significant variation in exposure exists even within these communities.
Such exposure to pollution has alarming health implications, as noted by Duarte. The Bronx, having the poorest air quality among all New York City boroughs, also sees asthma rates that are 2.5 times higher than in other areas.
“The repercussions of pollution exposure manifest in the hospitalization rates of adults in the Bronx,” Duarte observes.
The study was conducted in the fall of 2021, a period still affected by the global Covid-19 pandemic, meaning current mobility patterns in the Bronx may differ slightly. However, the researchers believe their methodology can inspire future studies examining pollution exposure.
Ratti points out that mobile data, along with pollution sensors on vehicles, can function as a vast monitoring system. “It’s cost-effective, builds on current infrastructure like cars and buses, and simply adding sensors enables improved air quality monitoring,” he states.
Wang emphasizes that detailed studies like this can be expanded to include analyses of other air quality hazards apart from PM 2.5 particulates. “This paves the way for new research into various toxicity issues in conjunction with exposure,” he adds.
The research received support from the MIT Senseable City Lab Consortium.
