To better understand air pollution in Allegheny County, which ranks 19th worst in the nation for short-term particle pollution according to the American Lung Association, Pitt Public Health researchers are comparing air quality across the county.
Their findings revealed substantial differences in pollution exposure across Allegheny County, with fine particulate matter concentrations varying as much as five-fold between neighborhoods and rising during colder months.
The study, published in July in Environmental Science and Pollution Research, used data collected through the Reducing Outdoor Contaminants in Indoor Spaces (ROCIS) initiative to provide residents with low-cost air monitoring tools, guided feedback and strategies to reduce their exposure.
“Allegheny County consistently scores failing grades on the American Lung Association’s State of the Air reports, and Pittsburgh ranks among the worst U.S. metropolitan areas for particle pollution,” said Abdul Alobireed (PhD, EOH '26) a recent graduate in the Department of Environmental and Occupational Health at Pitt Public Health.
While many previous studies have focused on either indoor or outdoor air, this study evaluated data collected over a six-year period, capturing both simultaneously.
“The beauty of what ROCIS was doing is that they captured simultaneous indoor and outdoor measurements,” said Nesta Bortey-Sam, PhD, associate professor of environmental and occupational health. “That simultaneous, long-term measurement was a major advantage.”
Using low-cost air monitors from 290 homes enrolled in ROCIS, researchers focused on fine particulate matter, or PM2.5—tiny airborne particles measuring 2.5 micrometers or smaller that can penetrate deep into the lungs and even enter the bloodstream.
Common outdoor sources include vehicle emissions, industrial pollution and wildfire smoke, while indoor sources can include tobacco smoke, cooking, burning candles and using air fresheners.
The researchers found substantial geographic differences in PM2.5 concentrations across Allegheny County, with some neighborhoods experiencing levels as much as five times higher than others.
Hotspots included Sewickley, southeastern Allegheny County near Clairton, as well as areas within Pittsburgh, including communities with environmental justice concerns.
“The biggest highlight is that there is a five-fold variation between neighborhoods,” Alobireed said. “We found hotspots throughout the county, with particularly elevated concentrations around Clairton and in parts of Pittsburgh.”
But geography alone did not determine exposure. Researchers found that poor air quality can affect communities throughout the region, even those farther from major industrial sources or at higher elevations.
“People don’t realize that living high on a hill doesn’t completely shield you,” said Linda Wigington, Team Leader for ROCIS (Reducing Outdoor Contaminants in Indoor Spaces). “Everyone in the region is affected, though some more than others.”
Pollution levels also varied by season, with researchers finding higher concentrations during colder months compared with warmer months.
“When we modeled the data, cold seasons showed much higher pollution levels compared to warmer seasons,” Alobireed said. “A big part of that comes from heating choices in the winter—such as people using fireplaces or wood-burning stoves, alongside outdoor bonfires, which contribute to outdoor pollution that may find its way inside.”
The simultaneous monitoring also gave researchers insight into how outdoor pollution moves indoors—and how activities inside the home can contribute to residents’ exposure.
For participants, the results sometimes challenged assumptions about where the pollution they were breathing was coming from.
“Some assumed outdoor air was totally dominant and were surprised by how much their indoor habits contributed,” Wigington said. “Others focused entirely indoors and were shocked by how much outdoor air affected them.”
For Bortey-Sam, one of the strengths of ROCIS is that the initiative does more than collect pollution data. Participants receive regular feedback to help them understand their measurements and identify ways to reduce their exposure.
“They don’t just collect numbers and walk away,” Bortey-Sam said. “They meet with residents weekly to explain what the data means—whether levels are high, low or in-between—and teach them practical mitigation strategies. That education is what truly stays with residents.”
Alobireed is completing a companion study examining how outdoor particle levels and household characteristics affect indoor air quality.
Moving forward, the group hopes to continue giving Allegheny County residents actionable tools to protect themselves from pollution while making the project’s extensive dataset more accessible for future research.
“In an ideal world, what we do isn’t just a research project—it’s giving people actionable tools to protect themselves from outdoor pollution and reduce indoor sources,” Wigington said.
Other authors of the study include Samantha Totoni and James Fabisiak, both of the University of Pittsburgh School of Public Health
-Ava Dzurenda