between November 4,1994 and May 9,1996, no NO2 measure were made. Therefore, for the polynomial distributed lag models, only the period without missing values were considered (from May 10,1996 to November 30,1997). Data were more complete for the other pollutant. Missing values were replaced with the mean of the prior and following days. Due to the difference in time series lenght, specific modeling was done to evaluate the effect of NO2