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Table 1 Summary statistics of daily ILI counts, PM2.5, and weather conditions in Beijing, China, during January 1, 2008 to December 31, 2014 (Q1, Q2 and Q3 denote the 25th, 50th and 75th percentile, respectively)

From: Impact of ambient fine particulate matter (PM2.5) exposure on the risk of influenza-like-illness: a time-series analysis in Beijing, China

Variable Flu season (October-April) Non-flu season (May-September)
Mean ± SD Minimum Q1 Q2 Q3 Maximum Mean ± SD Minimum Q1 Q2 Q3 Maximum
Daily ILI counts by age groups
 <5 695.45(227.78) 270 529 673 815 1717 657.45(152.24) 357 539 648 782 1088
 5–14 448.38(250.29) 124 311 389 505 2794 349.26(86.40) 153 289 341 406 710
 15–24 191.29(225.80) 32 90 119 205 2097 104.44(25.47) 44 86 103 120 197
 25–59 356.89(294.82) 79 179 246 429 1627 218.73(63.67) 78 176 211 260 512
 60+ 71.24(53.97) 10 40 54 83 381 51.52(22.86) 16 38 48 62 447
Fine airborne particulate matter (μg/m 3)
PM 2.5 100.66(80.86) 2.92 44.50 77.62 131.00 568.00 90.14(53.24) 9.79 52.25 83.26 115.70 463.00
Meteorological Measures
 Temperature 7.13(8.87) −12.50 −0.90 6.35 14.72 26.60 25.09(3.36) 11.20 23.30 25.60 27.50 34.50
 Humidity 47.39(19.82) 8 30 46 63 95 59.86(17.63) 13 48 63 73 97