| By Monique Mulima Early fall is when asthma flare-ups peak in the US, and a warming climate is bad news for sufferers: It means more ground-level ozone, a longer pollen season and more wildfire smoke — all triggers for people with respiratory conditions.  Smoke shrouds houses in Los Angeles during the Saddleridge Fire in October 2019. Wildfire smoke is a special irritant for people with respiratory conditions. Photographer: Allison Zaucha/Bloomberg While people with asthma or chronic obstructive pulmonary disease (COPD) can experience worse symptoms due to climate change, many of the medications they're prescribed also contribute to warming by emitting potent greenhouse gases. Pharmaceutical companies are looking to change that with lower-emitting inhalers that they plan to roll out by the end of the decade. Metered-dose inhalers — pressurized devices that release a puff of medicine into the mouth — make up the majority of the inhalers used in the US, according to data from 2019. They currently rely on hydrofluorocarbon (HFC) propellants. These chemicals, which are also used in air conditioning and refrigeration, are greenhouse gases far more powerful than carbon dioxide. Inhalers account for around 0.03% of global greenhouse gas emissions. But in the US, where metered-dose inhalers dominate, their emissions alone in 2020 were equivalent to those from driving almost 600,000 gas cars for a year or burning over 2.7 billion pounds of coal. "We're trying to treat conditions like asthma and COPD with these inhalers, and we're actually making it harder to breathe," said Jyothi Tirumalasetty, a clinical assistant professor at the Stanford University School of Medicine. Dry-powder inhalers — which a patient uses by sucking in a powdered medicine — and soft mist inhalers, which have a cartridge that releases a mist that is inhaled, have a far lower climate toll. A study that Tirumalasetty co-authored, published in August in the Journal of the American Medical Association, found these inhalers have a carbon footprint around 30 times smaller than that of metered-dose inhalers. Dry powder inhalers can be substituted for metered-dose types by a majority of patients but can also come at a higher price, and some people may lack the lung capacity to use them, or prefer metered-dose options. Those using a rescue inhaler during an asthma attack, especially, may want a propellant to help push the medicine into their airways. This is why GSK Plc is focusing on lowering the emissions of propellant rescue inhalers, said Laura Clow, a medicine development leader at the company. GSK's metered-dose Ventolin inhaler, prescribed to around 35 million people globally, accounts for 49% of the company's entire carbon footprint. GSK has entered phase three of trials for a new propellant for Ventolin. Currently each inhaler produces the equivalent of 24 kilograms of carbon emissions, but with the new propellant that will come down to 2 kilograms, Clow said. The dose, look and feel of the new inhalers will be the same, she said, with only the propellant changing. GSK expects to submit regulatory filings for the updated inhaler in 2025 and to complete a full transition to the new propellant by 2030. AstraZeneca Plc recently completed the studies and clinical program for a propellant with 99.9% lower emissions for its COPD metered-dose maintenance inhaler, Breztri. The company plans to file for regulatory approval in the UK, Europe and China by the end of 2024, and then file in other countries in 2025. Whatever kinds of inhalers are used, when people can keep their respiratory condition under control, it means there's less need for emergency interventions. That's helped by early detection, affordable drug prices and governments working to reduce air pollution and wildfires, said Albert Rizzo, chief medical officer at the American Lung Association. "Those of us who have underlying lung conditions are going to have more flare-ups due to those climate change effects in the air quality," he said. "More flare-ups means more cost to the healthcare industry, more hospitalizations and poor quality of life for these individuals." You can read and share a full version of this story on Bloomberg.com. For unlimited access to climate and energy news and original data and graphics reporting, please subscribe. | 
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