A growing evidence base shows that chronic obstructive pulmonary disease (COPD) is affected by climate and environmental exposures, not only through extreme temperature exposure and air pollution but also through wildfire smoke and other potential natural disasters, said Nadia N. Hansel, MD, professor of medicine at Johns Hopkins University, Baltimore, in a presentation at the GOLD International COPD Conference in Philadelphia.

Indoor and outdoor pollutants and climate extremes have shown association with COPD exacerbations separately, but these factors also can act synergistically to increase morbidity in patients with high-risk COPD, said Hansel.

Air Quality’s Impact

Several studies have shown associations between higher levels of particulate matter in the air and increased risk for respiratory symptoms, exacerbations, and mortality in patients with COPD, she said. A 2021 study by Rosana Aguilera and colleagues showed a potential association between wildfire smoke and health effects, due not only to an increase in particulate matter and other pollutants but also to an increase in the toxicity of the particles. In addition, ambient ozone has been associated with an increased risk for COPD and emphysema exacerbation, as well as increased respiratory symptoms, Hansel said.

However, efforts to improve air quality can mitigate or reverse some negative effects, said Hansel. For example, a study in JAMA showed improvement in bronchitic symptoms in children with improved indoor air quality. Another study published in The New England Journal of Medicine showed an attenuation of age-related lung function decline after a reduction in exposure to higher levels of air pollution.

Indoors, air pollution is also associated with an increased respiratory morbidity in former smokers with COPD, Hansel said in her presentation. This can be due to cigarette smoke as well as nonsmoking sources. Hansel and colleagues conducted an initial study in 2013 that showed a significant association between increased indoor particulate matter and severe COPD exacerbations, respiratory symptoms, respiratory-specific quality-of-life scores, and use of rescue medication in former smokers with COPD. The study has been replicated twice with similar results, Hansel said.

Temperature Takes a Toll

Extremes of both hot and cold temperatures have been associated with an increased mortality in patients with COPD, Hansel said. A 2025 study by Kexin Yu and colleagues examined more than 2 million COPD deaths among individuals in China. The researchers found an association between heat waves and mortality during the study period from 2013 to 2019.

In a 2019 study, lower winter outdoor temperatures were significantly associated with increased inhaler use, increased COPD symptoms, and reduced lung function on the basis of forced expiratory volume per second. In addition, indoor temperatures may also affect respiratory morbidity. For example, daily minimum indoor temperature was associated with respiratory symptoms, as measured by the breathlessness, cough, and sputum scale when the indoor median temperature was < 70 °F.

Considering Synergy

A combination of indoor heat and outdoor air pollutants was worse than either alone and associated with an increased use of rescue inhalers, based on data from a study by Hansel and colleagues. This burden is disproportionate in underserved communities, where individuals in substandard housing with limited resources to mitigate environmental factors are at an increased risk for both high pollutant burden and extreme temperatures, Hansel noted.

In a study published in 2022, Hansel and colleagues explored whether indoor air cleaners can improve indoor air quality and improve health for individuals with COPD. They found that high-efficiency particulate absolute (HEPA) air cleaners may improve respiratory health for this patient population by reducing particulate matter. In particular, a reduction in particulate matter of more than 40% was associated with improved respiratory health. By contrast, air cleaners’ reduction in indoor nitrogen dioxide had no significant impact on COPD symptoms in this study.

In another study currently in press, Hansel and colleagues found that even among active smokers, HEPA filtration and motivational interviewing techniques to reduce indoor smoking burden suggest that the use of indoor air cleaners for smokers with COPD can result in improved respiratory health. These early results suggest that nonpharmacologic strategies such as air filtration could improve respiratory health for individuals with chronic disease, although these interventions remain understudied, Hansel said.

Education and Intervention

Individuals living with COPD are among the most vulnerable to environmental changes driven by climate change, Alexander Rabin, MD, told Medscape Medical News. “Extreme temperatures, including both heatwaves and cold snaps, along with higher levels of outdoor ozone and particulate matter from air pollution and wildfire smoke, have all been linked to increased COPD-related exacerbations and mortality,” said Rabin, clinical associate professor of pulmonary and critical care medicine at the University of Michigan, Ann Arbor, Michigan. “These effects are compounding, acting together to worsen respiratory health,” he added.

Regarding the use of nondrug interventions to improve indoor air quality for patients with COPD, potential barriers include cost and access to effective air cleaners, limited awareness of indoor pollution sources, housing conditions that limit feasibility of interventions, and challenges with maintaining sustained use, Rabin said. “These barriers may be overcome through education, behavioral strategies such as motivational interviewing, integration of indoor air quality counseling into routine COPD care, and targeted monetary subsidies for high-risk patients,” he noted.

Looking ahead, “More work is needed to define clinically meaningful targets for indoor air pollutant reduction and to define which COPD subgroups benefit most from interventions like air cleaners,” said Rabin. “Longer-term trials also are needed to understand the impact of interventions on lung function decline, respiratory exacerbations, and, critically, the cost-effectiveness of interventions in underserved settings,” he added.

Hansel disclosed receiving research support from and serving on advisory boards for AstraZeneca and GlaxoSmithKline, as well as receiving a donation from Austin Air Cleaner. Rabin disclosed having no financial conflicts of interest.