How air pollution and extreme temperatures affect emergency hospital admissions due to various respiratory causes in Spain, by age group: A nationwide study

This study set out to use specifically calculated dose-response functions to analyse how air pollution and extreme temperatures affected short-term daily emergency admissions due to respiratory diseases (asthma, upper respiratory tract infections and pneumonias) in the general population, children under 14 years of age and adults over 65 years of age, in all Spanish provinces across the period January 1, 2013─December 31, 2018. The following independent variables were used: mean daily NO₂, PM₁₀, PM_2.5 and O₃ concentrations recorded at all air pollution monitoring stations situated in the respective provinces; and maximum and minimum daily temperatures measured at reference observatories. Using generalised linear models (GLM) with a Poisson link, and controlling for trend, seasonalities and the autoregressive nature of the series, we calculated the relative risks for statistically significant associations. These were then used to calculate attributable risks and attributable cases, for the purpose of drawing up an economic estimate. Overall, chemical air pollution was linked to 33063 (95 %CI: 13536-55404) respiratory-cause admissions, which accounted for 7.8 % of total admissions in Spain. Respiratory-cause admissions attributable to heat- and cold-wave temperatures totalled 5754 (95 %CI: 2506, 8611), i.e., a lower order of magnitude. Nationwide, the impact of NO₂ and O₃ was greater than that of PM. The percentage of attributable admissions was higher in the under-14 than in the 65-year age group for all pollutants except ozone. This shows that the implementation of health-prevention plans that included temperature-pollution factors would be an effective way of mitigating the impacts which extreme temperatures and pollution have on population health.