The statistical analysis was conducted in two phases. In the first part, area-specific time-series models were used for the analysis as EAD, air pollution and meteorological data are linked by date. Poisson regression generalized linear models (GLM)were used to fit the time-series data.
A natural cubic spline function was used to control for long-term trends and seasonality, as well as the daily mean temperature and relative humidity. We used 7 degrees of freedom (df) per year for time trends.