Air pollution in urban areas is commonly measured with fixed measuring points which are spread over the entire city. New York is one of these cities with an extensive monitoring network of 155 locations. On the other side, we are nearly to 100 percent trackable – with the smartphone in our pocket. Researchers at the Massachusetts Institute of Technology (MIT) tried to use this smartphone data in order to receive new insights to provide a deeper picture of air pollution in urban areas.
According to the related study “Exposure Track—The Impact of Mobile-Device-Based Mobility Patterns on Quantifying Population Exposure to Air Pollution“, published in the journal Environmental Science & Technology, spatially- and temporally varying populations can be considered. With the tracked population dynamic and activity patterns, it is possible to evaluate the population-weighted exposure to air pollution on a city-wide scale. Allegedly, it is the first study using measured population activity patterns of several million people to quantify population-weighted exposure to air pollution in urban areas with the support of mobile phones.
The study states:
In investigating the temporal variability of the “Active” population-weighted exposures determined in districts, these were found to be significantly different (p < 0.05) during the daytime and the nighttime. Evaluating population exposure to air pollution using spatiotemporal population mobility patterns warrants consideration in future environmental epidemiological studies linking air quality and human health.
Three different maps of New York illustrate a comparison of approaches to measuring pollution exposure.
“The traditional way to look at pollution is to have a few measurement stations and use those to look at pollution levels,” says Carlo Ratti, a professor of the practice in MIT’s Department of Urban Studies and Planning, and director of MIT’s Senseable City Lab, where the study was conducted. “But that’s sensitive to where the [measuring] stations are. If you want to quantify exposure, you also need to know where people are.”
MIT News states:
Specifically, the flow of people into parts of midtown Manhattan, and some parts of Brooklyn and Queens close to Manhattan, appeared to increase aggregate exposure to PM in those areas. Meanwhile, the daytime movement of people away from Staten Island actually lowered overall exposure levels in that borough.
“Up to now, much of our understanding of the impact of air pollution on population health has been based on the relationship between air quality and mortality and/or morbidity rates, in a population which is assumed to be at their home location all the time,” says Marguerite Nyhan, a researcher at Harvard’s T.H. Chan School of Public Health, who led the study as a postdoctoral researcher at the Senseable City Lab. “Accounting for the movements of people will improve our understanding of this relationship. The findings will be important for future population health assessments.”
121 days of data from April through July 2013 were examined by the scientists. According to MIT News, this method can be applied broadly for urban and environmental analysis.
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