Inhalers warm the planet as much as half a million cars

Inhalers help millions of people breathe easier each day and can often be a lifeline for many who suffer from a host of respiratory diseases. A new study reveals that while inhalers can potentially save lives, they are major contributors to global warming.

The researchers estimated that inhalers in the U.S. released more than 2 million metric tons of CO₂-equivalent emissions each year over the past decade. That’s roughly equal to the annual emissions from about 530,000 gasoline-powered cars on the road.

Most of the climate impact comes from pressurized inhalers that use hydrofluoroalkane (HFA) propellants. These are synthetic gases that trap heat hundreds to thousands of times more effectively than carbon dioxide.

Estimating emissions from inhalers

Dr. William B. Feldman and his team at the David Geffen School of Medicine at UCLA linked national dispensing data to device-specific emissions factors.

Inhalers are often prescribed for asthma or COPD, a long-term lung disease that makes it hard to breathe. COPD is usually caused by smoking or pollution.

The researchers looked at all approved inhalers from 2014 to 2024, and then estimated emissions by drug, device, propellant, and care setting.

Pressurized metered-dose inhalers use a liquefied gas to push medicine out of a canister. The team found that these devices were responsible for 98 percent of all inhaler-related emissions over the past decade.

Types of inhalers linked to emissions

Three types of inhalers made up the largest share of emissions. Short-acting beta-agonists are fast-acting drugs that relax airway muscles to quickly relieve asthma symptoms.

Inhaled corticosteroids (ICS) reduce inflammation and swelling in the airways, helping to prevent flare-ups.

ICS–LABA combination inhalers include both a steroid to control inflammation and a long-acting drug that keeps airways open for longer periods.

Upward trend in emissions

The trend line ran upward. Annual emissions linked to inhalers rose from about 1.9 million metric tons in 2014 to 2.3 million metric tons in 2024.

The researchers also estimated the social cost of emissions by looking at the economic damage caused by each ton of greenhouse gas released. This damage was associated with health and climate impacts of 5.7 billion dollars over the course of the decade.

The researchers warn that the gas is the root of the problem. The global warming potential translates grams of propellant – the pressurized gas that pushes medicine out of the inhaler – into large chunks of climate impact.

More sustainable inhaler options

Several analyses show how much change is possible within the same medicines and dose schedules.

Some inhalers do not contribute to global warming. Dry powder inhalers and soft mist inhalers deliver medication without propellants.

For these types of inhalers, the emissions burden shifts to manufacturing and disposal, which are much smaller per inhaler than the propellant effect.

One analysis found that switching appropriate patients from pMDIs to reusable soft mist devices could reduce emissions by roughly 10 percent to more than 90 percent, depending on regimen and class. Those are population averages, not one-size-fits-all rules.

However, some patients need pressurized devices for clinical reasons, including those who cannot generate enough inspiratory flow. The strength and speed of a person’s breath when inhaling affects how well certain inhalers work.

Change starts in the medical community

“Inhalers add to the growing carbon footprint, the total amount of greenhouse gases caused directly or indirectly by an activity or product, of the US health care system, putting many patients with chronic respiratory disease at risk,” said Dr. Feldman.

“On the upside, there is a tremendous opportunity to make changes that protect both patients and the planet by utilizing lower-emission alternatives.”

That sentiment pairs with the data in a straightforward way. Keep patients’ needs first, but when the drug and dosing are the same, prescribe the lower emission device.

The same goes for procurement. Hospitals and clinics can track device-level emissions as part of purchasing, then prioritize lower-emission options where clinical criteria are met.

Future of climate-friendly inhalers

The U.S. inhaler market is not static. As HFC allowances tighten, manufacturers are exploring low-GWP propellants for future pressurized products. These innovations still need clinical evidence and regulatory review before they can scale.

The authors plan to compare outcomes within the same drug classes across device types. That will help sharpen prescribing guidance and help payers align coverage with options that cut emissions without tradeoffs in control or exacerbation risk.

Patients should not carry this burden alone. Clear labeling, device training, refill counseling, and disposal programs can make it easier to choose and stick with the right inhaler for health and for the climate.

The study is published in the journal JAMA.

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