Cheap device can measure air pollution everywhere | MIT news

Air pollution is a major public health problem: the World Health Organization estimates that it leads to more than 4 million premature deaths worldwide each year. However, it is not always measured extensively. But now an MIT research team is rolling out an open-source version of a low-cost, mobile pollution detector that will allow people to monitor air quality more broadly.

The detector, called Flatburn, can be made through 3D printing or by ordering low-cost parts. The researchers have now tested and calibrated it against existing state-of-the-art machines, and are publicly releasing all the information about it – how to build it, use it and interpret the data.

“The goal is that community groups or individual citizens anywhere can measure local air pollution, identify the sources and, ideally, create feedback loops with officials and stakeholders to create cleaner conditions,” said Carlo Ratti, director of MIT’s Senseable City Laboratory.

“We’ve done several pilots around the world and we’ve refined a series of prototypes, with hardware, software and protocols, to make sure the data we’re collecting is robust from an environmental science perspective,” said Simone Mora, a research scientist at Senseable City Lab and co-authored a newly published paper detailing the scanner’s testing process. The Flatburn device is part of a larger project known as City Scanner, which uses mobile devices to better understand city life.

“Hopefully, with the release of the open-source Flatburn, we can get grassroots groups and communities in less developed countries to adopt our approach and build and share knowledge,” said An Wang, a researcher at Senseable City Lab and another of the co-authors of the article.

The article, “Using machine learning algorithms to advance low-cost air sensor calibration in stationary and mobile settings,” appears in the journal Atmospheric environment.

In addition to Wang, Mora and Ratti, the study’s authors are: Yuki Machida, a former research fellow at Senseable City Lab; Priyanka deSouza, assistant professor of urban and regional planning at the University of Colorado at Denver; Tiffany Duhl, a researcher with the Massachusetts Department of Environmental Protection and a Tufts University research associate at the time of the project; Neelakshi Hudda, a research assistant professor at Tufts University; John L. Durant, professor of civil and environmental engineering at Tufts University; and Fabio Duarte, principal investigator at Senseable City Lab.

The Flatburn concept at Senseable City Lab dates back to about 2017, when MIT researchers began prototyping a mobile pollution detector, originally intended for use on garbage trucks in Cambridge, Massachusetts. The detectors are battery powered and rechargeable, either from power sources or a solar panel, with data stored on a card inside the device that can be accessed remotely.

The current expansion of that project included testing the devices in New York City and the Boston area, by seeing how they performed against already operating pollution detection systems. In New York, the researchers used 5 detectors to collect 1.6 million data points over four weeks in 2021, working with government officials to compare the results. In Boston, the team used mobile sensors to evaluate the Flatburn devices against a state-of-the-art system deployed by Tufts University in conjunction with a government agency.

In both cases, the detectors were set up to measure concentrations of particulate matter and nitrogen dioxide over an area of ​​about 10 metres. Particulate matter refers to tiny particles commonly associated with burning matter, from power plants, automotive combustion engines and fires, and more.

The research team found that the mobile detectors estimated slightly lower particulate matter concentrations than the devices already in use, but with a strong enough correlation that, with adjustments for weather conditions and other factors, the Flatburn devices can provide reliable results.

“After following their implementation for a few months, we can confidently say that our low-cost monitors should behave similarly [as standard detectors]Wang says. “We have a big vision, but we still need to make sure that the data we collect is valid and can be used for regulatory and policy purposes,”

Duarte adds: “If you follow these procedures with low-cost sensors, you can still collect good enough data to go back to. [environmental] agencies with it and say, ‘Let’s talk.’”

The researchers found that using the units in a mobile environment – on top of cars – means they currently have a lifespan of six months. They also identified a range of potential problems that people in general will face when using the Flatburn detectors. These include what the research team calls “drift,” the gradual change of the detector’s readings over time, as well as “ageing,” the more fundamental deterioration in a unit’s physical condition.

Still, the researchers believe the units will function properly and provide full instructions on releasing Flatburn as an open-source tool. That even includes guidelines for working with officials, communities and stakeholders to process the results and take action.

“It is very important to engage with communities so that they can think about sources of pollution,” says Mora.

“The original idea of ​​the project was to democratize environmental data, and that is still the goal,” adds Duarte. “We want people to have the skills to analyze the data and engage with communities and officials.”

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