Concerns over health care’s carbon footprint typically revolve around issues like overly-air-conditioned hospitals and single-use medical supply waste. But researchers like Stanford University’s Jyothi Tirumalasetty think that asthma inhalers are also a good place to start when it comes to reducing emissions.
Metered-dose inhalers, the most common type used to treat asthma or chronic obstructive pulmonary disease (COPD), use a propellant gas to aerosolize medications, which patients then breathe in. Those propellant gasses are usually one of two different hydrofluorocarbons — which are many times better at trapping heat in the atmosphere than carbon dioxide, and thus disproportionately contribute to climate change.
Allergist Tirumalasetty, along with University of Michigan professor Shelie Miller and other co-authors, analyzed 2022 data from Medicare and Medicaid to figure out the average greenhouse gas emissions of these inhalers, and compare their costs to more environmentally friendly options.
STAT spoke with Tirumalasetty about the study, released today in JAMA, and what the takeaways are for people who use inhalers.
This interview has been lightly edited and condensed for length and clarity.
Are inhalers a big contributor to climate change, in the grand scheme of things?
Our numbers showed that for the year 2022, for the Medicare-Medicaid population, that amount of emissions [from inhalers] is equivalent to powering all the homes in a city approximately the size of Milwaukee for an entire year.
HHS has pledged that they want to reduce [emissions] by 50% by 2030 and 100% by 2050. And a lot of institutions have signed on to that pledge. And so where do we start reducing emissions in health care? We know health care is about 8-10% of our national emissions yearly. And so even if this is a fraction of that, it’s a good place to start.
What did the study find?
We are prescribing mostly metered-dose inhalers. Those are the inhalers that contain those greenhouse gas propellants, and those inhalers are contributing about 98% of the emissions from all inhalers. And we are spending way more on the environmentally friendly alternatives — the majority of those would be the dry powder inhaler category.
We’re finding that CMS spent $2.5 billion more on these dry powder inhalers, even though they are prescribed far less frequently than the ones that contain the propellants.
I thought — maybe naively — that hydrofluorocarbons (HFCs) were phased out a couple decades ago.
Those are CFCs [chlorofluorocarbons] — the Montreal Protocol phased those out [in the early 2000s]. We took them out of inhalers and we replaced them with HFCs. So the CFCs were depleting the ozone layer. And the HFCs are greenhouse gas propellants that are thousands of times more powerful in trapping heat than carbon dioxide — they have a much higher global warming potential than carbon dioxide.
So we went from one not-so-great propellant to a different, not-so-great propellant — or propellants, I should say, since there are two that are used in these inhalers. That’s why [some inhalers] have super-high emissions compared to others; it really varies widely within these metered-dose inhalers. There were some that had emissions of like 15 [kilograms of estimated carbon dioxide equivalents per inhaler] and then others that were like 48. So there’s definitely better choices even within those. It’s not that everybody has to go to a dry powder. We could even lower our emissions by going [to] lower-emission metered-dose inhalers.
And we might get zero emissions propellants coming … and so that’ll be much better for the environment. It’s just that [when we get the new inhalers] — and this happened when we saw the CFCs go away and HFCs come — they rebrand the inhaler, they sell it with the new brand name, and then it becomes more expensive and it becomes a higher tier on the insurance coverage, and we think it’s going to be a while before those are accessible to everyone.
Is it safe for people to inhale these hydrofluorocarbon propellants in the first place?
It’s safe. When you use [an inhaler], the medication goes into your lungs. But the majority of that propellant is going to come back out when you breathe it out. And so, whether you spray into the air or you’re inhaling it and breathing it out, that’s going to go into the atmosphere and eventually trap heat. It’s not damaging the ozone; it’s not a pollutant that is damaging to us. It’s trapping heat and creating an increased warming effect of the atmosphere. And that’s where the problem is.
It’s also going to be left in the inhaler after you’re done with it — about 30% may be left in there. If you toss it in the garbage, it’s going to slowly leak out over time. There’s no recycling programs for inhalers in the U.S. right now … There’s a place in the U.K. that does it — they repurpose the greenhouse gas and [sell it back to] the heating and cooling industry. And some places can actually recycle the aluminum canister and some places are able to recycle the plastic, [but] that’s really not being done at a large scale in the U.S.
Are there reasons why the more environmentally friendly inhalers are less prescribed, besides cost?
I’m an allergy-immunology doctor. I’ve been treating asthma for two decades now, and I think it has to do with some of it has to do with cost, some of it has to do with patient preference, some of it has to do with just tradition: “Hey, this inhaler has been around a long time. This is what we’re used to. So we’re going to prescribe this.” Even though some of these newer inhalers, the dry powder ones, are a lot more user-friendly for many types of people and they are designed where you only have to do them once a day, so they lead to more compliance versus a lot of the older metered-dose ones.
Other countries have now really moved to using the dry powder ones because they’re trying to reduce their emissions. In the U.K., they’ve implemented programs across the country to decrease the use of the propellant-containing inhalers. And same thing with Canada. I think the U.K., the last time I checked they were at about 50/50, so they’ve come down on their use of the propellant-containing inhalers. In Sweden, it’s about 80% of the dry powder and mist inhalers, the ones that don’t contain the propellants.
I think that if we are more aware that there’s other options, if we are more aware that the ones that we’re using a lot of are not great for the environment, I think that people would be more willing to maybe consider other options.
What would a movement to switch look like? Is it a policy change? Is it deprioritizing it on [prescription drug] formularies, is it physician education?
I think it’s all of those things. And when I speak to people who are practicing in the U.K., they tell me that their patients know that these inhalers aren’t great for the environment and they’re invested in lowering their own carbon footprints, and that they ask for environmentally friendly inhalers.
This is not something that we would recommend in small children. We know that there are limitations to people switching to environmentally friendly inhalers. It [depends on] whether or not they’re able to take a deep breath … And we don’t have great trials that compare dry powder inhalers to metered-dose inhalers, the environmentally friendly ones to the non-environmentally friendly. We don’t have recent strong studies in the U.S. that can really clearly delineate which one’s better, which one’s easier to use.
But I would say a program like that would really require educating physicians on making sure to make the decision with their patients — making sure that the patient, if they have a preference, that they’re not switching them unwillingly. We don’t want any patient to feel bad or forced to switch. We don’t want anyone to not have access to their asthma inhaler. We want to use what’s best for them and what’s best for the environment, whenever that’s possible.
What’s the takeaway from this study? Is it for physicians to look at the chart you have and figure out how to prescribe lower-emission inhalers for their patients?
Absolutely. We are looking to reduce our emissions in health care, and we want to analyze what we’re doing and say, “Hey, at which step can we reduce our emissions?” And if there’s an easy way to do it where we’re not compromising care, so we’re choosing the best inhaler for the patient and the best inhaler for the environment, whenever that’s possible, then that’s what we would like for people to do.
And we want to be very forthright about, “Hey, this may cause increased spending on these inhalers because these dry powder ones and these soft mist ones tend to be more expensive; we aren’t sure why that is.” But we know that they are very efficacious drugs and that many places have switched to those and are having great outcomes. That’s really the takeaway. And for everything we do in medicine — whether it’s in the OR, it’s in anesthesia — that we start to think about the carbon footprint of health care, because a lot of people are not having those discussions.
We also hope that this will lead to some policy changes — that maybe the Centers for Medicare and Medicaid Services can, under the Inflation Reduction Act, negotiate better prices for environmentally friendly inhalers, which will be an incentive for people to prescribe them more.