JUANA SUMMERS, HOST:

Millions of people depend on asthma inhalers, but most people don't know that using those inhalers creates a carbon footprint. That's according to a new study published in the medical journal JAMA this week. But as Alejandra Borunda from NPR's climate desk reports, there is a climate-friendly alternative.

ALEJANDRA BORUNDA, BYLINE: Dr. Jyothi Tirumalasetty of Stanford University has worked with asthma patients for years. She has prescribed a lot of inhalers in her time. And most of those are what's called metered dose.

JYOTHI TIRUMALASETTY: Metered-dose inhalers are kind of the classic inhaler that you would think about when you see someone with asthma or COPD puffing on something.

BORUNDA: That little puff pushes medications into people's lungs, and it's powered by gases called hydrofluorocarbons. They're incredibly potent greenhouse gases, some more than 1,000 times as powerful as carbon dioxide. But until recently, that wasn't well known to the medical community.

TIRUMALASETTY: Everyone who's involved in asthma treatment, everyone I talked to, they were like, oh, we didn't know about this. And I certainly had no idea about it.

BORUNDA: The climate impact of inhalers had been calculated in other countries like the U.K., but not in the U.S. until Tirumalasetty and some colleagues did the math. They looked at data for about 40% of the country's prescriptions and found that inhalers had a big climate footprint. On average, using one is like...

TIRUMALASETTY: Driving about 59 miles in your average gasoline-powered car.

BORUNDA: Added up, it's the equivalent of home energy use in a city roughly the size of Madison. But there's an alternative. Many patients could use what's called a dry powder inhaler. It delivers medication without the gassy puff, so its climate impacts are much lower. Dr. Samantha Green is a family physician at Unity Health in Toronto.

SAMANTHA GREEN: I mean, most people are horrified at the magnitude of the carbon pollution created by their inhaler, and they're happy to make that switch.

BORUNDA: It can take a little time to adjust to the powder inhaler, and they're not recommended for everyone. But Green says they can work for many, and they're common elsewhere.

GREEN: In other countries - Continental Europe, Sweden - actually the majority of inhalers that are prescribed are dry powdered inhalers.

BORUNDA: Others like the U.K. are trying to use more of the climate friendly option. But it's complicated in the U.S. Dry powder inhalers often cost more and aren't always readily available. And Tirumalasetty stresses that it is not an asthma patient's responsibility to shoulder their medications' climate cost, but everyone knowing more could eventually help move the needle.

Alejandra Borunda, NPR News. Transcript provided by NPR, Copyright NPR.

NPR transcripts are created on a rush deadline by an NPR contractor. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.