Dr. Jyothi Tirumalasetty, M.D., says research is zeroing in on propellants known as HFCs or hydrofluorocarbons. They push the medicine out of the inhaler in measured doses but can also escape into the atmosphere at alarming levels.
"These HFCs are hydrofluorocarbons and propellants, which now we know trap heat in the atmosphere thousands of times more powerfully than carbon dioxide and increase, you know, worse, global warming," Tirumalasetty said.
She says some inhalers can emit as much greenhouse gas as the average gasoline-powered car driven for 60 miles.
To better understand those levels, Tirumalasetty and her colleagues used safety data and prescription records for inhalers in the U.S. They found traditional devices, known as metered dose inhalers, release the most HFCs -- about 98% of the total -- but also vary widely from brand to brand.
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"There's a range within the meter dose inhalers. Some of them have less propellant. Some of them have more. So, it can be anywhere as low as nine for one inhaler and 48 for another, depending on how much propellant and which propellant is in there," she said.
Other types, including dry-powder inhalers and soft-mist inhalers, are typically far less polluting. But depending on insurance and other factors, they can be significantly more expensive. Researchers say a goal of the study is to help decision-makers, as well as doctors and patients to better understand the tradeoffs. Possibly influencing the future evolution of a medical device millions of people rely on to breathe freely.
And with one possible solution already on the horizon, they say at least one manufacturer is working on a low-polluting version of the traditional inhaler.