Climate Change, Air Pollution, and COPD Outcomes: Response

Abstract

We thank Dr Hernàndez-Garduño and colleagues for their close reading and questioning of our recent article.1Bernstein AS Rice MB Lungs in a warming world: climate change and respiratory health.Chest. 2013; 143: 1455-1459Abstract Full Text Full Text PDF PubMed Scopus (49) Google Scholar We take this opportunity to address their concerns. There are two comments from the authors with which we agree. The first is that while climate may influence COPD hospitalization rates, it remains unclear which specific indications for COPD hospitalization are most affected. We agree that more research could reveal with greater specificity which pathophysiologic mechanisms are involved. Their second comment relates to how barometric pressure might influence oxygen saturation based on a single small study.2Dockery DW Pope 3rd, CA Kanner RE Martin Villegas G Schwartz J Daily changes in oxygen saturation and pulse rate associated with particulate air pollution and barometric pressure.Res Rep Health Eff Inst. 1999; : 1-19PubMed Google Scholar Long-term changes in barometric pressure have not been considered a major consequence of higher concentrations of greenhouse gases, but there may be more variability in barometric pressure as a result of climate instability, with potential consequences for patients with COPD. We presented findings that indicate greenhouse gases may worsen air quality by increasing ground-level ozone and promoting forest fires, which release a variety of air pollutants, including particulate matter < 2.5 μm in diameter (PM2.5). Dr Hernàndez-Garduño and colleagues mention the relationship between PM2.5 exposure and cardiorespiratory mortality and argue that air pollutants need to be included in models that assess health effects of climate change. Of the studies we referenced on acute effects of heat waves on respiratory hospitalizations or mortality, both adjusted for ozone3Lin S Luo M Walker RJ Liu X Hwang SA Chinery R Extreme high temperatures and hospital admissions for respiratory and cardiovascular diseases.Epidemiology. 2009; 20: 738-746Crossref PubMed Scopus (289) Google Scholar, 4Monteiro A Carvalho V Oliveira T Sousa C Excess mortality and morbidity during the July 2006 heat wave in Porto, Portugal.Int J Biometeorol. 2013; 57: 155-167Crossref PubMed Scopus (70) Google Scholar; additionally, Monteiro et al4Monteiro A Carvalho V Oliveira T Sousa C Excess mortality and morbidity during the July 2006 heat wave in Porto, Portugal.Int J Biometeorol. 2013; 57: 155-167Crossref PubMed Scopus (70) Google Scholar adjusted for PM2.5. Future studies should continue to consider the complex interplay of air pollution and climate. Dr Hernàndez-Garduño and colleagues make a further blanket critique of air pollution/climate change and COPD research, stating that there are “too many factors to be considered” and inevitably confounded results. Of a lengthy list of variables they name, including smoking history, obesity, and β-blocker use, almost none are associated with both the exposure (eg, heat waves) and outcome (COPD hospitalization) and as such cannot be confounders. Temperature, humidity, and season of the year are included in almost all models of acute health effects of air pollution and, in climate research, are often the primary exposures of interest. Despite the many challenges of climate and air pollution research, we maintain that their critique underestimates the quality and consistency of the epidemiologic studies in the literature. Although it is true that most studies of COPD hospitalization in relation to air pollution or climate are based on administrative data, we disagree that these studies have poorly adjusted for confounding. We reiterate that climate change puts at risk the health of millions of people around the world with chronic lung diseases. Physicians are uniquely positioned to understand and communicate the importance of reducing greenhouse gas emissions for the welfare of patients. Climate Change, Air Pollution, and COPD Outcomes: Too Many Factors to Be Considered, Even Barometric Pressure!CHESTVol. 144Issue 5PreviewA recent article by Bernstein and Rice1 published in CHEST (May 2013) reminds us that climate change may be the single greatest health threat of this century. The authors provided an excellent review focusing on the effects of climate variables on common chronic respiratory diseases, namely asthma and COPD. Some of the studies mentioned include the effects of acute increases in temperature, humidity, ambient ozone, or exposure to wildfire smoke on ED visits or hospitalization due to COPD or asthma. Full-Text PDF