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.