Untangling the Inequitable Effects of Heat and Air Pollution on Human Health

Shanghai Origins

This ambitious research project can be traced all the way back to 2017. For several months, Bergin, Jim Zhang, professor of global and environmental health at Duke, and a host of colleagues from multiple international institutions monitored the indoor air quality of the homes of a few dozen asthmatic children in Shanghai, China. Armed with commercial air filters and inexpensive DIY sensors, the team tried to determine if in-home filters could improve the short-term health of these children constantly breathing some of the most polluted air on Earth.

Researchers were not sure if a single air filter placed in the bedroom of a child could impact their health given the relatively small amount of time spent there, but the results were clear. Not only did air filters improve the children’s health, they did so after only two weeks of use. The results also suggested that consistent use could not only help alleviate flare-ups, but potentially prevent them altogether.

According to Bergin, the relatively small study sparked dozens of impactful papers on the chemical composition of particulate matter and volatile organic compounds (VOC’s) that people in the study were exposed to. It also helped reveal the sources of air pollutants, relationships between exposures and activities of the participants, and the development of novel biomarker approaches to assess health impacts.

That success led to a multimillion-dollar partnership between Duke and Underwriters Laboratory to assess the impact of air pollution, including wildfires, and heat on human health. Wildfires commonly produce PM_2.5 particles, which have a diameter of less than 2.5 micrometers—about three percent of the diameter of a human hair—and have been shown to have a dramatic effect on human health because of their ability to travel deep into the lungs.

Listen to Mike Bergin talk about his experiences building and deploying low-cost air quality sensors across the globe.

While Bergin’s expertise has long been in the engineering of low-cost, DIY air-quality sensors that can be distributed at scale, Carlson has added the secret sauce when it comes to data analysis and AI. Partnering together on the project, the two have been able to show that, for example, across Durham there can be a huge difference (almost 10 degrees F) in temperatures on the hottest days. Also, the makeup of indoor air pollutants varies greatly across town. They are currently trying to figure out how the combination impacts people’s mental and physical health.

But that’s not the only time the two have teamed up.

First Durham, Then the World

All of this work has now come to a head. Years of first-hand experience seeing what air pollution can do to vulnerable populations and how big of an impact an in-home air filter can make. Multiple papers showing that heat islands in urban areas are an underappreciated and under-accounted problem. Decades of experience building low-cost sensors for wide-scale deployment and analyzing the resulting data. A longstanding partnership with UL, a company with the resources and convictions to help.

But even the most ambitious projects have to start somewhere. Why not Durham?

Bergin, Carlson and Danielle Wagner, a postdoctoral researcher at Duke, have recruited over a dozen homes in Durham to begin their quest. Working from the ground up, they have spread the word at the South Durham Farmer’s Market, showed up at local environmental action groups, and reached out through the Keep Durham Beautiful listserv. They have also worked with local partners Clean AIRE NC and the El Futuro Greenspace team to gain insights and perspectives for these efforts.

“Bringing awareness to all the heat-related issues that we have in our community is something that’s very important—not only for El Futuro, but for the broader Latino community in Durham,” said Gian Carlos Carmona, who works with El Futuro Greenspace and Community Engagement. “Many people are greatly affected by the issues we’re experiencing this summer and not always able to manage them.”

The result of all this work and recruitment is the Hot Durham Project (short for Distributed Urban Residential Air Quality and Heat Monitoring). Each participating home had a reliable weather station installed in their yard to keep tabs on the heat and humidity levels. They have also had low-cost commercial air quality monitors installed. Last but not least, each participant has been given an Oura ring to track biometrics like heart rate, sleep, activity levels and other indicators of how heat and air pollution might be impacting their lives.

“We’ve tried to space the households all across the city so that we’re not just getting places near Duke, which is cooler than some parts because of all the trees on campus,” Wagner said. “The hope is to find overlaps between the effects of heat and air quality, like patterns of when it’s hotter at night and people are getting less sleep quality or their heart rate variability is not as healthy as usual.”

There’s a good chance they’ll succeed. Already they have found differences of single-day highs between participating households as large as 12 degrees Farenheit. Just imagine for a moment how different 100 degrees outside feels compared to 88 degrees. Carbon dioxide levels have also been found over three times higher at one home than another on the same summer day, indicating that improving cooling by closing up homes can often lead to higher indoor air pollution levels.

Perhaps the best part of taking the time to install all these sensors is that the data can be easily pulled without having to interrupt the residents’ lives again. Simple coding allows the team to collect the data remotely and incorporate it into a dashboard built by Alain Soto, an undergraduate student, where it can be easily viewed and integrated into models.

With all of these tools in hand, the team hopes to go well beyond simply showing how big of an impact the combination of heat and air pollution can have on people’s lives. Thanks to data analysis led by Lucy Gagnon, a PhD student, results can reveal specific volatile compounds found across Durham as well as each household’s emission sources, whether that be burning candles and incense, cleaning with intense chemicals, or fermenting cider in their living rooms.

In a long-term study such as this, participants being able to see their own environmental data in real-time through their own dashboards is rare. To help make sense of it all, Anna Clauer, a graduate student, worked with Clean AIRE NC, UL Research Institute’s Chemical Insights, and the Museum of Life and Sciences to create individualized reports explaining their household emissions and heating and cooling profiles along with strategies and local resources available for mitigating these exposures.

“As just one example, if you don’t have proper ventilation when cooking from something like a window or a stove hood, that can drastically change your exposure levels, not just to heat but to air pollutants,” Wagner said. “When people know what to avoid, they can figure out how to minimize their risks.”

The Hot Durham Project team hopes that all of these resources will help keep participants engaged for the long haul.

“The biggest challenge to a project like this is finding people who are committed for the long term, beyond the initial excitement of getting started,” said Carlos. “I feel like that’s something we’ve found working alongside the group that we have here at El Futuro. We want to bring resources to the people who need them, and that starts with educating people about these issues.”