Short-term effects of chemical and noise pollution during heat and cold waves on emergency hospital admissions in Madrid.

Cold and heatwaves and air pollution have a joint, direct impact on population health. The aim of this study was to evaluate the combined impact of chemical air and noise pollution on hospital admissions during warm and cold months, with a breakdown by age group. We conducted a time-series study of unscheduled emergency admissions by specific causes in Madrid across the period 2013-2018. The independent variables were daily mean concentrations of PM2.5, PM10, NO2, tropospheric ozone, noise, and maximum and minimum temperatures. Relative and attributable risks were calculated using generalised linear models with a Poisson link. During the warm months, stronger associations were found between: ozone and admissions due to respiratory, circulatory and neurological causes; NO2 and admissions due to respiratory diseases; and PM and admissions due to dementia and Alzheimer's disease. Heat had a greater effect on admissions due to neurological diseases. During the cold months, no association was found with any chemical air pollutant, except for NO2 and asthma-related admissions. By age, the greatest impacts were registered for PM, noise, cold and heat at ages ≥ 65 years, and for noise, NO2 and cold at ages ≤ 14 years.