By replacing the current inhalers for conditions such as asthma with alternative, greener ones may result in large carbon savings and reduced drug costs, according to a study released on Wednesday by the University of Cambridge.

Metered-dose inhalers for patients who have asthma and other conditions usually contain liquefied, compressed gases that act as a propellant to atomize the drug being delivered and to pump it out to the user.

These inhalers usually use hydrofluoroalkane (HFA) propellants, which are potent greenhouse gases. However, effective alternatives are already available, such as dry powder inhalers and aqueous mist inhalers.

A team of researchers from the University of Cambridge and other institutions studied NHS prescription data from England in 2017 and collated carbon footprint data on inhalers commonly used in England in order to compare the financial and environmental costs of different inhalers.

They found that the carbon footprints of metered-dose inhalers were between 10 to 37 times those of dry powder inhalers.

At 2017 prescription levels, replacing one in ten metered-dose inhalers in England with the cheapest equivalent dry powder inhalers could lead to a reduction in drug costs of 8.2 million pounds (10.6 million U.S. dollars) annually and would reduce a significant amount of carbon emissions, according to the study.

"Our study shows that switching to inhalers which are better for the environment could help individuals, and the NHS as a whole, reduce their impact on the climate significantly. This is an important step towards creating a zero carbon healthcare system fit for the 21st century," said Dr James Smith, consultant in Public Health from the Department of Public Health and Primary Care at the University of Cambridge.

The study has been published in the journal BMJ Open.