The relationship of lung function with ambient temperature

BACKGROUND: Lung function is complex trait with both genetic and environmental factors contributing to variation. It is unknown how geographic factors such as climate affect population respiratory health. OBJECTIVE: To determine whether ambient air temperature is associated with lung function (FEV(1)) in the general population. DESIGN/SETTING: Associations between spirometry data from two National Health and Nutrition Examination Survey (NHANES) periods representative of the U.S. non-institutionalized population and mean annual ambient temperature were assessed using survey-weighted multivariate regression. PARTICIPANTS/MEASUREMENTS: The NHANES III (1988–94) cohort included 14,088 individuals (55.6% female) and the NHANES 2007–12 cohort included 14,036 individuals (52.3% female), with mean ages of 37.4±23.4 and 34.4±21.8 years old and FEV(1) percent predicted values of 99.8±15.8% and 99.2±14.5%, respectively. RESULTS: After adjustment for confounders, warmer ambient temperatures were associated with lower lung function in both cohorts (NHANES III p = 0.020; NHANES 2007–2012 p = 0.014). The effect was similar in both cohorts with a 0.71% and 0.59% predicted FEV(1) decrease for every 10°F increase in mean temperature in the NHANES III and NHANES 2007–2012 cohorts, respectively. This corresponds to ~2 percent predicted difference in FEV(1) between the warmest and coldest regions in the continental United States. CONCLUSIONS: In the general U.S. population, residing in regions with warmer ambient air temperatures was associated with lower lung function with an effect size similar to that of traffic pollution. Rising temperatures associated with climate change could have effects on pulmonary function in the general population.