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Introduction: This systematic review examines how extreme temperatures impact chronic obstructive pulmonary disease (COPD) morbidity and mortality, focusing on identifying vulnerable subpopulations., Methods: We conducted a systematic literature search from January 1, 2000, to November 6, 2024, across databases like PubMed, MEDLINE and EMBASE, Web of Science, and Scopus, focusing on observational studies that quantitatively defined extreme temperatures and their impacts on COPD morbidity and mortality. Out of 3140 records, 25 studies met the inclusion criteria. We extracted data on study characteristics, effect estimates, and confounders, employing methods to assess the risk of bias and synthesize results., Results: We observed that extreme heat increased the relative risk (RR) for COPD morbimortality by 1.16-fold (95 % CI: 1.08-1.26; p < 0.05), and extreme cold increased the RR by 1.32-fold (95 % CI: 1.20-1.46;). Extreme heat was associated with a 1.19-fold (95 % CI: 1.09-1.30; p < 0.05) increase in COPD mortality. In contrast, extreme cold was associated with both COPD morbidity and mortality, with morbidity increasing by 1.47-fold (95 % CI: 1.26-1.71; p < 0.05) and mortality by 1.23-fold (95 % CI: 1.10-1.38; p < 0.05). Extreme heat poses a higher risk for female COPD patients compared to males. Moreover, extreme heat and cold were associated with morbimortality risk among older adults. Asian populations were sensitive to both temperature extremes, whereas Europeans were predominantly susceptible to extreme cold., Conclusion: This variability in response to extreme temperatures affects COPD morbidity and mortality, emphasizing the need for tailored medical and emergency responses to effectively mitigate health risks during extreme weather events., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The impact of short-term exposure to environmental factors such as temperature, relative humidity (RH), and fine particulate matter (PM 2.5 ) on chronic obstructive pulmonary disease (COPD) remains unclear. The objective of this study is to investigate PM 2.5 as a mediator in the relationship between short-term variations in RH and temperature and COPD severity. A cross-sectional study was conducted on 930 COPD patients in Taiwan from 2017 to 2022. Lung function, COPD Assessment Test (CAT) score, and modified Medical Research Council (mMRC) dyspnea scale were assessed. The mean and differences in 1-day, 7-day, and 30-day individual-level exposure to ambient RH, temperature, and PM 2.5 were estimated. The associations between these factors and clinical outcomes were analyzed using linear regression models and generalized additive mixed models, adjusting for age, sex, smoking, and body mass index. In the total season, increases in RH difference were associated with increases in forced expiratory volume in 1 s (FEV 1 ) / forced vital capacity (FVC), while increases in temperature difference were associated with decreases in FEV 1 and FEV 1 /FVC. Increases in PM 2.5 mean were associated with declines in FEV 1 . In the cold season, increases in temperature mean were associated with decreases in CAT and mMRC scores, while increases in PM 2.5 mean were associated with declines in FEV 1 , FVC, and FEV 1 /FVC. In the warm season, increases in temperature difference were associated with decreases in FEV 1 and FEV 1 /FVC, while increases in RH difference and PM 2.5 mean were associated with decreases in CAT score. PM 2.5 fully mediated the associations of temperature mean with FEV 1 /FVC in the cold season. In conclusion, PM 2.5 mediates the effects of temperature and RH on clinical outcomes. Monitoring patients during low RH, extreme temperature, and high PM 2.5 levels is crucial. Capsule of findings The significance of this study is that an increase in ambient RH and temperature, as well as PM 2.5 exposure, were significantly associated with changes in lung function, and clinical symptoms in these patients. The novelty of this study is that PM 2.5 plays a mediating role in the association of RH and temperature with COPD clinical outcomes in the short term., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The impacts of climate change and air pollution on respiratory diseases present significant global health challenges. This review aims to investigate the effects of the interactions between these challenges focusing on respiratory diseases. Climate change is predicted to increase the frequency and intensity of extreme weather events amplifying air pollution levels and exacerbating respiratory diseases. Air pollution levels are projected to rise due to ongoing economic growth and population expansion in many areas worldwide, resulting in a greater burden of respiratory diseases. This is especially true among vulnerable populations like children, older adults, and those with pre-existing respiratory disorders. These challenges induce inflammation, create oxidative stress, and impair the immune system function of the lungs. Consequently, public health measures are required to mitigate the effects of climate change and air pollution on respiratory health. The review proposes that reducing greenhouse gas emissions contribute to slowing down climate change and lessening the severity of extreme weather events. Enhancing air quality through regulatory and technological innovations also helps reduce the morbidity of respiratory diseases. Moreover, policies and interventions aimed at improving healthcare access and social support can assist in decreasing the vulnerability of populations to the adverse health effects of air pollution and climate change. In conclusion, there is an urgent need for continuous research, establishment of policies, and public health efforts to tackle the complex and multi-dimensional challenges of climate change, air pollution, and respiratory health. Practical and comprehensive interventions can protect respiratory health and enhance public health outcomes for all., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Air pollution has been reported to be associated with chronic obstructive pulmonary disease (COPD). Our study aim was to examine the mediating effects of air pollution on climate-associated health outcomes of COPD patients. A cross-sectional study of 117 COPD patients was conducted in a hospital in Taiwan. We measured the lung function, 6-min walking distance, oxygen desaturation, white blood cell count, and percent emphysema (low attenuation area, LAA) and linked these to 0-1-, 0-3-, and 0-5-year lags of individual-level exposure to relative humidity (RH), temperature, and air pollution. Linear regression models were conducted to examine associations of temperature, RH, and air pollution with severity of health outcomes. A mediation analysis was conducted to examine the mediating effects of air pollution on the associations of RH and temperature with health outcomes. We observed that a 1 % increase in the RH was associated with increases in forced expiratory volume in 1 s (FEV 1 ), eosinophils, and lymphocytes, and a decrease in the total-lobe LAA. A 1 °C increase in temperature was associated with decreases in oxygen desaturation, and right-, left-, and upper-lobe LAA values. Also, a 1 μg/m 3 increase in PM 2.5 was associated with a decrease in the FEV 1 and an increase in oxygen desaturation. A 1 μg/m 3 increases in PM 10 and PM 2.5 was associated with increases in the total-, right-, left, upper-, and lower-lobe (PM 2.5 only) LAA. A one part per billion increase in NO 2 was associated with a decrease in the FEV 1 and an increase in the upper-lobe LAA. Next, we found that NO 2 fully mediated the association between RH and FEV 1 . We found PM 2.5 fully mediated associations of temperature with oxygen saturation and total-, right-, left-, and upper-lobe LAA. In conclusion, climate-mediated air pollution increased the risk of decreasing FEV 1 and oxygen saturation and increasing emphysema severity among COPD patients. Climate change-related air pollution is an important public health issue, especially with regards to respiratory disease., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)