The effect of short-term temperature modified by air pollution on cardiorespiratory function

BACKGROUND AND AIM: The combined effect of short-term exposure to temperature and air pollution on cardiorespiratory function is largely unknown. We investigated the short-term effect of ambient temperature when modified by air pollution on cardiorespiratory function. METHODS: We investigated 420 elderly women from the German SALIA cohort during the 2012-2013 follow-up examination. The combined outcome of cardiorespiratory function was calculated as standardised (mean zero, standard deviation one) sum of the lung function z-scores for forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and systolic and diastolic blood pressure values, which were themselves standardised and transformed so that higher values reflect better cardiorespiratory function. The short-term temperature-air pollution effect on cardiorespiratory function was assessed over lag 0-4 days, with the air pollutant centred to the 25th and 75th quantile, using multivariable regression models with distributed lag non-linear models. RESULTS:For low temperatures, cardiorespiratory function declined by -0.27 (95%CI: -0.83, 0.29) during low ozone (O3) days, and -0.22 (95%CI: -0.88, 0.44) during high O3 days. The opposite relationship was observed for high temperatures, with cardiorespiratory function increasing by 0.06 (95%CI: -0.62, 0.75) during low O3 days, and 0.12 (95%CI: -0.45, 0.70) during high O3 days, respectively. Additionally, cardiorespiratory function declined on low temperature days by -0.46 (95%CI: -1.24, 0.31) during low PM10 days, and -0.50 (95%CI: -1.07, 0.08) during high PM10 days; however, the effect of high temperatures on cardiorespiratory function when adjusted for the different PM10 levels differed, with cardiorespiratory function decreasing by -0.05 (95%CI: -0.68, 0.58) during high PM10 days, while increasing by 0.09 (95%CI: -0.59, 0.77) during low PM10 days. CONCLUSIONS:Temperatures were inversely associated with cardiorespiratory function in elderly women, with the effect size being more apparent for low temperatures. Strength varied according to air pollution levels, however results were not statistically significant. KEYWORDS: Temperature, Air Pollution, Cardiorespiratory, Climate Change, Cohort study.