The Human Studies Facility is an unremarkable six-story red-brick building on the medical school campus of the University of North Carolina (UNC) at Chapel Hill. But for 30 years, this laboratory, run by the US Environmental Protection Agency (EPA), led the world in investigating respiratory hazards.
Its scientists used nine human exposure chambers to prove cause and effect between pollutants and health outcomes. Their work informed air-pollution policy not only in the United States, but also around the world.
On 30 June, however, the facility shut its doors after the US government refused to renew its long-standing lease with the university. This is a significant loss, and comes at a crucial moment for respiratory health, says Robert Devlin, a former senior EPA scientist who worked at the lab throughout its 30-year run. Without the facility, Devlin says, there will be no way to find out whether current air-quality standards are safe and protective. “We’ll no longer be able to answer the question.”
Nature Outlook: Lung health
An EPA spokesperson declined to answer Nature’s questions and instead stated that “all of the functions from this lab are in the process of or have been transferred” to another EPA facility in nearby Research Triangle Park, and that Nature’s sources “seem to be grossly misinformed”. Devlin says that such a move is impossible. The facility’s exposure chambers alone occupy around 1,860 square metres and require specialized engineers to maintain. “The exposure facility is unique and is not able to be transferred,” Devlin says. “To be blunt, they are lying.”
The World Health Organization (WHO) estimates that air pollution causes 7 million premature deaths each year, globally. Actions to improve air quality have saved lives. In the United States, for example, research1 suggests that annual deaths attributed to air pollution almost halved between 1990 and 2010, from 135,000 to 71,000. In 43 European countries, air-pollution deaths dropped by 42% between 1990 and 2019, from an estimated 639,000 to 368,0002. But in the United States, an alarming trend is emerging. For the first time in decades, concentrations of fine-particulate pollution have stopped declining in many places3. And in some areas, they are rising. According to a report (see go.nature.com/4oaolv7) released in April 2025 by the American Lung Association, nearly half of people in the United States now live with unsafe levels of air pollution. “The severity of the problem and abruptness of the change are unprecedented,” the authors of the report write. That trend will continue, specialists such as Devlin say, if the administration of President Donald Trump moves forward with its plans to roll back environmental regulations and to increase the use of fossil fuels.
Some of the threats to lung health come from well-known air pollutants such as ozone and particulate matter generated by vehicles. But a suite of emerging respiratory hazards — including increasingly intense wildfires, spore-spread fungal diseases and airborne microplastic — is adding urgency to the issue. Many of these hazards are poorly understood, and the harm that they cause seems to be worse when combined with other stressors, such as extreme heat. “It’s a double whammy,” says Mary Rice, a pulmonary physician and environmental-health researcher at Harvard University in Cambridge, Massachusetts.
The closure of the Human Studies Facility is not the only way in which US scientists are being hampered in their effort to investigate and respond to these emerging hazards, Devlin says. In July, the Trump administration announced that the EPA’s entire research branch, the Office of Research and Development (ORD), would be dissolved. The EPA spokesperson said that this restructuring would “improve the effectiveness and efficiency of EPA operations” and “allow EPA to prioritize research and science more than ever before.” Although the agency has announced its intention to create a new Office of Applied Science and Environmental Solutions, this will report directly to the EPA administrator, which was not the case previously. “The big concern is that this EPA administrator intends to be very active in setting the scientific agenda”, Devlin says.
Scientists have been left scrambling to fill knowledge gaps and prepare for the future. “We need to understand what the threats are and also what we can actually do to protect people,” says Ilona Jaspers, an inhalation toxicologist at the UNC at Chapel Hill. But without government grants and support, the large, multi-site studies needed to do this will not be feasible, she says. “We are losing the capabilities and infrastructure to prepare.”
Heterogenous hazard
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