Fig. 2. Daily number of ED visits for AE in each age group during the 5-year study period (0-2 years, infants; 2-5 years, preschool children; 6-17 years, school children; 18-59 years, adults; >60 years, elderly). Blue solid lines indicate fits to Fourier regression (first 8 consecutive sinusoidal functions), and indicate 1 cycle per year in the old age group, and 2 cycles per year in the other groups. ED, emergency department; AE, asthma exacerbation.