Inhalers’ emissions: A new analysis suggests that the inhalers millions of Americans rely on to breathe also carry a sizable climate footprint, roughly the same annual emissions as more than 5,30,000 cars in the United States.
Researchers from UCLA and Harvard reviewed prescription data for asthma and COPD medicines used between 2014 and 2024 by people covered through commercial insurance, Medicaid, and Medicare. Their study, published in JAMA, estimates these devices generated 24.9 million metric tons of CO₂ equivalent over the decade.
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The main culprit is the common pressurised metered-dose inhaler (MDI), or “puffer.” MDIs rely on hydrofluoroalkane (HFA) propellants, potent greenhouse gases, to deliver medicine to the lungs and account for about 98% of the inhaler-related emissions tallied. By comparison, dry powder inhalers (DPIs) and soft-mist inhalers do not use propellants: DPIs are breath-activated, and soft-mist devices atomise liquid medication; both options carry a far smaller carbon footprint.
Clinically, MDIs are still necessary for some groups, like very young children who need spacers to coordinate breaths, and some frail older adults who cannot generate sufficient inhalation force. But the study notes that most patients could be treated effectively with DPIs or soft-mist devices, as seen in countries such as Sweden and Japan, without sacrificing outcomes.
So why hasn’t the US shifted faster? The authors point to insurance coverage and market barriers. A dry-powder version of albuterol, the most commonly used rescue medicine, exists but is often not covered, pushing up out-of-pocket costs. Meanwhile, budesonide–formoterol, widely available in DPI form in Europe, has limited availability in the US market. The researchers stress the onus should not fall on patients; rather, policy and pricing reforms are needed to make lower-emission options broadly affordable.
A related commentary in JAMA warns that upcoming “low-global-warming” MDIs may enter the market as high-priced brand-name products, potentially widening access gaps if insurers do not adjust coverage. The authors urge payers and policymakers to ensure greener inhalers are accessible and affordable, so patients aren’t forced to choose between respiratory health and climate impact.
