Ambient air temperature and temperature variability affecting blood pressure—a repeated-measures study in Augsburg, Germany

Ambient air temperature and temperature variability are supposed to influence blood pressure (BP); however, findings are inconsistent. We examined the effects of short-term changes in ambient temperature and temperature variability on systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP) in a repeated-measures study. Repeated BP measurements were available for 3184 participants from the German population-based Cooperative Health Research in the Region of Augsburg (KORA) S4 survey (1999–2001) and two follow-up examinations (2006–08 and 2013–14). Daily meteorological data were obtained from fixed measurement stations including air temperature and diurnal temperature range (DTR). We used confounder-adjusted additive mixed models to examine immediate (same-day, lag 0), delayed (lag 1 to lag 4), and cumulative (up to lag 0–13) exposure effects. Decreases in air temperature were associated with increases in SBP, DBP, and MAP, while we observed no effects for PP at all. For example, a 1 °C decrease in the 14-day moving average (lag 0–13) mean air temperature was associated with a 0.54% [95% confidence interval [95%CI]: 0.41%;0.68%] increase in SBP. Furthermore, decreasing DTR was linked to increasing SBP, DBP, and MAP measures. In the sensitivity analyses, results were found to be robust. Examination of exposure–response functions according to season revealed, that associations for summer and winter can be considered linear, while we detected non-linear functions in spring and autumn. Furthermore, exposure–response functions also differed in the three different surveys. As BP levels influence the risk of cardiovascular mortality, our results show the importance of considering temperature and its variation as potential risk factors. As ongoing climate change affects temperature variability, it is important to understand how the body adapts to changing ambient temperatures.