The study, published in JAMA Internal Medicine, found that inhalers with a lower carbon footprint in one commonly used therapeutic class—the combined long-acting muscarinic antagonist (LAMA)-long-acting beta agonist (LABA) class—were associated with slightly better clinical outcomes for patients with COPD compared to metered-dose inhalers (MDIs) in the same class. MDIs are commonly prescribed, but they rely on propellants—potent greenhouse gases also used in aerosol sprays—to deliver medication to the lungs. In contrast, dry powder and soft mist inhalers do not use these propellants and therefore have a substantially lower global warming potential.

Researchers also found that these lower-emission inhaler types were more effective at preventing COPD exacerbations without increased safety risks. The dry powder inhaler, umeclidinium-vilanterol, was associated with a 14% lower risk of moderate or severe COPD exacerbations compared with the MDI, glycopyrrolate-formoterol. The soft mist inhaler, tiotropium-olodaterol, was associated with a 6% lower risk of exacerbations compared with the metered-dose option.