Inhalers used to treat asthma and chronic obstructive pulmonary disease (COPD) generate greenhouse gas emissions equivalent to more than half a million cars each year in the United States, according to a new study published in JAMA, October 2025. Researchers say the findings highlight an overlooked source of health care–related carbon pollution and call for a shift toward lower-emission devices.
The study, conducted by researchers at Brigham and Women’s Hospital and Harvard Medical School, analyzed U.S. inhaler use from 2014 to 2024. It found that nearly all emissions came from metered-dose inhalers (MDIs), which use hydrofluoroalkane (HFA) propellants to deliver medication.
Emissions Equivalent to 530,000 Cars
The research team estimated that inhalers dispensed in the United States over the ten-year period produced about 24.9 million metric tons of carbon dioxide equivalent (CO₂e). In 2024 alone, emissions from inhalers reached about 2.3 million metric tons, roughly the same as the annual output of 530,000 gasoline-powered cars.
About 1.6 billion inhalers were dispensed during the study period, with emissions rising by nearly 25 percent since 2014. The increase reflects growing use of inhaled medications and continuing reliance on MDIs rather than lower-emission alternatives.
“Metered-dose inhalers account for about 98 percent of inhaler-related greenhouse gas emissions in the U.S.,” said lead author Dr. William B. Feldman told to phys.org. “There’s a tremendous opportunity to reduce emissions by prescribing devices that do not rely on these propellants.”
Propellants Identified as Main Source
The study found that the propellants inside MDIs—hydrofluoroalkanes—are potent greenhouse gases used to expel medication as an aerosol mist. Although the medication doses are small, the propellants’ high global warming potential (GWP) makes their cumulative impact significant.
Dry powder inhalers (DPIs) and soft-mist inhalers, which rely on patient inhalation or mechanical action rather than chemical propellants, were found to have a much lower carbon footprint.
The researchers calculated the social cost of inhaler-related greenhouse gas emissions—an estimate of the economic damages caused by climate change—at around $5.7 billion over the decade.
Albuterol and Steroid Inhalers Among Top Emitters
Among inhaler types, those containing albuterol, budesonide-formoterol, and fluticasone propionate were responsible for approximately 87 percent of all emissions. These medications are among the most commonly prescribed for patients with asthma and COPD.
The authors said that while inhalers are essential for controlling respiratory disease, the data show that alternative devices could substantially reduce emissions without compromising treatment effectiveness.
“There are clinically appropriate, lower-emission alternatives for many patients,” Feldman said. “We need to balance patient needs with the broader environmental consequences of care.”
Health Care’s Carbon Footprint Under Scrutiny
The findings add to growing evidence that the health-care sector contributes significantly to climate change. In the U.S., health care accounts for an estimated 8.5 percent of national greenhouse gas emissions, according to prior studies.
Inhalers represent a small but highly visible component of that total because of their direct link to hydrofluorocarbon emissions, a class of gases regulated under the Kigali Amendment to the Montreal Protocol, which aims to phase down HFCs worldwide.
Environmental analysts say the study could help policymakers and medical organizations identify “low-hanging fruit” in reducing the sector’s footprint.
“This research highlights a tangible and achievable way to cut emissions without sacrificing patient care,” said Dr. Julia Stevens, an environmental health expert not involved in the study. “It’s comparable to removing half a million cars from the road each year.”
Transition Faces Barriers
While the study recommends wider adoption of dry powder and soft-mist inhalers, researchers acknowledge that several barriers could slow the transition.
Clinical factors play a role: some patients, particularly the elderly or those with severe respiratory limitations, find MDIs easier to use. Cost and insurance coverage also affect prescribing decisions, as some greener alternatives remain more expensive or less widely available.
Physicians may also lack awareness of the environmental impact of different inhaler types, and pharmaceutical companies have limited incentives to redesign devices or invest in low-GWP propellants without regulatory pressure.
“Without policy support, the market alone may not drive the transition quickly enough,” Feldman said.
Industry Response and Next Steps
Several pharmaceutical manufacturers are already developing MDIs that use low-global-warming-potential propellants, such as hydrofluoroolefins (HFOs), which have a climate impact roughly 90 percent lower than conventional HFAs. Early prototypes are in regulatory review, but widespread adoption may take several years.
Health systems in Europe and the U.K. have begun encouraging physicians to switch to DPIs or soft-mist inhalers when clinically suitable. The National Health Service (NHS) in the U.K. has committed to cutting emissions from inhalers by 50 percent by 2030 as part of its broader “Net Zero Health Service” plan.
U.S. regulators have yet to announce specific targets, but the Environmental Protection Agency (EPA) is phasing down HFCs across multiple industries, and the new data could inform health-care-specific policies.
Call for Policy and Awareness Changes
The authors of the JAMA study suggest that medical associations, insurers, and federal agencies consider environmental impacts when drafting clinical and reimbursement guidelines. They recommend incentives for low-emission inhaler use, clearer labeling of device carbon footprints, and inclusion of sustainability metrics in pharmaceutical approval processes.
Public education could also help patients participate in emission-conscious decisions. Many users are unaware that their inhalers have differing environmental impacts, researchers said.
“If patients and clinicians are informed, they can choose equally effective options that are better for the planet,” Feldman noted.
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Global Relevance
Although the study analyzed U.S. data, experts say similar patterns are likely worldwide. Inhaler use is widespread across Europe, Asia, and Latin America, where millions of asthma and COPD patients rely on MDIs.
The global inhaler market is valued at more than $30 billion annually, and analysts predict growing demand as respiratory conditions increase in urban populations exposed to pollution and climate-related allergens. Without intervention, emissions from inhalers could continue to climb sharply.
Low- and middle-income countries may face additional challenges in shifting to greener technologies due to cost and supply constraints. International cooperation, including technology sharing and public-private partnerships, may be necessary to ensure access to low-emission devices.
Balancing Patient Health and Planetary Health
The authors of the JAMA study stress that patient safety remains the top priority. No one should stop or change inhalers without consulting a doctor. But they say that the health sector can make environmentally conscious choices without compromising care.
“Reducing emissions from inhalers is one of the most straightforward ways to make health care more sustainable,” Feldman said. “It’s a small change for each patient, but the cumulative effect is substantial.”
Experts agree that the transition to lower-emission inhalers could become a model for broader sustainability efforts in medicine, showing that better health and environmental stewardship can go hand in hand.
The new research adds urgency to calls for greener medical technologies. With inhalers responsible for millions of tons of carbon emissions each year—equivalent to hundreds of thousands of vehicles—the findings challenge both industry and policymakers to act.
If health systems can reformulate, redesign, and re-educate at scale, the humble inhaler could become one of the first success stories in decarbonizing health care—saving lives while helping the planet breathe a little easier. (Wage Erlangga)
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