The effect of temperature modified by season on lung function in the GINIplus/LISAplus cohort: A 15-year follow-up

Background and Aim Climatic variables such as temperature and relative humidity (RH) impact lung function in the elderly. However, there is little research on the effect of temperature on lung function in adolescents. This preliminary study aims to assess the effect of temperature modified by season on lung function in adolescents. Methods Spirometric lung function measurements (Forced vital capacity; FVC, forced expiratory volume; FEV1, and forced expiratory flow; FEF25-75%) were collected from GINIplus/LISAplus, two German birth cohorts at their 15-year follow up examination. A total of 2174 adolescents from the Wesel and Munich areas were assessed. We used generalised additive models to assess the linear effect of 8-day moving average temperature on FVC, FEV1, and FEF25-75%. The core model was adjusted for the 8-day moving average concentrations of RH, fine particulate matter (PM₂.₅) and ozone (O₃), and was stratified by season (warm or cold). Results We found that there was a decrease in FEF25-75% [relative risk (RR): 1.009 (95% Confidence interval (CI): 1.001 to 1.017)], FEV1 [RR: 1.013 (95%CI: 1.002 to 1.024)], and FVC [RR: 1.011 (95%CI: 1.001 to 1.021)] per 1°C increase in temperature (8-day moving average) during the warm season, respectively. Similarly, there was a decrease in FEF25-75%, and FEV1 when exposed to low mean temperature (8-day moving average) during the cold season, however, the results were not statistically significant. Conclusions Negative associations between prior exposure to 8-day temperature and lung function were apparent during the warm season but not necessarily in the cold season. The association remains robust after the addition of pollutants (PM₂.₅ and O₃). We speculate that a decline in lung function associated with warm temperature could be due to behavioural changes on relatively warm days, because of increased participation in outdoor activities. Keywords Temperature, respiratory health, climate change, air pollution