Date November 28, 2023
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New state-of-the-art sensor at Brown is enabling city-specific air quality measurements in Providence

A high-grade air quality sensor installed on Brown’s campus is providing detailed measurements of carbon dioxide and methane concentrations in Providence, painting a clearer picture of local air quality.

PROVIDENCE, R.I. [Brown University] — When it comes to climate change caused by greenhouse gas emissions, carbon dioxide and methane are the two biggest culprits. Yet beyond national, regional or state averages, many cities and towns don’t have the tools to capture clear data on how significantly these gases contribute directly to local air quality.

This has long been the case for Providence, Rhode Island — until now. A new, state-of-the-art sensor on
Brown University’s campus will ultimately help scientists, public officials and local community members get a better understanding of the air Rhode Islanders, and especially those in Providence, are breathing.

Installed in late October, the sensor recently began analyzing the air above Providence to continuously measure both methane and carbon dioxide, commonly referred to as CO2.

Previously, direct measurements on methane concentrations did not exist for Providence. Technically, neither did high-grade measurements on CO2, which came from instruments in Boston. That’s according to Meredith Hastings, a Brown professor of environment and society and Earth, environmental and planetary sciences who studies air pollution in the city and is leading the new effort.

“The idea here is to monitor both CO2 and methane much more locally both in real-time and over time,” Hastings said. “Being able to do this will help us understand our local air quality in terms of the major drivers and causes of pollution, so that we can potentially do something about it. The data we gather and share could also be a powerful tool in gauging whether we are meeting our sustainability goals on campus and, in the bigger picture, whether the city is reaching its own climate and carbon reduction goals.”

Hastings’ research team acquired the sensor with funds from a seed grant from Brown’s Office of Sustainability and Resiliency and installed it atop the University’s John D. Rockefeller Jr. Library on Prospect Street. The group plans to display the real-time measurements from the new sensor publicly online sometime in the spring and will also provide support for data interpretation to those looking to understand or utilize the data.

Measurements from the new air quality sensor, which also monitors for water vapor, will help Hastings’ team calibrate 22 low-cost sensors they previously installed across the city as part of the Breathe Providence Project. Part of a global initiative supported by the Clean Air Fund, the project involves testing for seven pollutants across Providence neighborhoods, including CO2, carbon monoxide, nitrogen oxides and particulate matter such as dust, soot and smoke.

Overall, the goal of Breathe Providence is to create a neighborhood-scale air quality monitoring network to understand the major drivers of air pollution events in the city and their links to health outcomes, such as high asthma rates in adults and children in south and central Providence neighborhoods.

Currently, the group uses high-quality CO2 measurements captured in Boston to calibrate the low-cost sensors for CO2, undercutting some of the ability to pinpoint levels in the air more locally. The new CO2 and methane analyzer, which cost about $55,000, will make the low-cost sensors, which cost about $3,000 each, more accurate for measuring CO2, because readings from the new sensor will be based in the same area as they are instead of dozens of miles away.

Providence, like many New England cities, suffers from high ozone events and earned an “F” grade in the most recent State of the Air Report from the American Lung Association. Emission figures may be underestimated by up to 60%, according to a 2021 study in Nature Communications. And when it comes to methane, which is about 25 times more potent than CO2, research is showing that methane leaks are prevalent in cities, like Providence, that have increasingly older infrastructure.

The sensor, made by the environmental company Picarro, is located in a corner of the Rockefeller Library’s attic space where it has access to outdoor air, is protected from inclement weather and has a prime location above the city for measuring air quality.

“You can see highways; you can see downtown; you can see neighborhoods; you can see trees,” Hastings said. “All of these are contributing to our carbon footprint, so we wanted the sensor to sit somewhere where the air is fairly well mixed so that we get a sense of that scale, which is what we want it to be measuring.”

The measurements from the sensor are considered gold standard in the industry, Hastings said, and researchers plan to keep the system running 24 hours a day.

Along with calibrating the Breathe Providence sensors and providing baseline data for carbon reduction goals in the city, the researchers hope the new data will also support research related to campus decarbonization outlined in the University’s strategic plan for sustainability — one of the reasons the project was selected for seed funding, said Liz Guthrie, Brown’s sustainability and Living labs program manager. Other projects funded by Sustainability Seed Grants include re-purposing 3D print material for use on campus and an effort to create climate action kits for K-12 public schools.

Another of Hastings’ biggest hopes for the project is that the measurements eventually influence a shift in how local governments support better air quality, which to date have relied largely on regional averages instead of on hyper-local data: “People don’t breathe average air,” Hastings pointed out.