Skip to main content

Advertisement

Table 1 Distribution of referent and non-referenta days by city

From: Associations between ambient air pollutant mixtures and pediatric asthma emergency department visits in three cities: a classification and regression tree approach

  Atlanta Dallas St. Louis
  Referent (n = 606) Non-referent (n = 3406) Referent (n = 121) Non-referent (n = 1261) Referent (n = 115) Non-referent (n = 2239)
Month N % N % N % N % N % N %
January 106 17.49 229 6.72 15 12.40 107 8.80 25 21.74 190 8.49
February 41 6.77 270 7.93 6 4.96 107 8.80 5 4.35 192 8.58
March 26 4.29 315 9.25 14 11.57 110 9.05 1 0.87 203 9.07
April 12 1.98 318 9.34 3 2.48 117 9.62 5 4.35 205 9.16
May 24 3.96 317 9.31 10 8.26 114 9.38 4 3.48 213 9.51
June 15 2.48 315 9.25 13 10.74 107 8.8 0 -- 207 9.25
July 9 1.49 332 9.75 8 6.61 116 9.54 0 -- 186 8.31
August 18 2.97 323 9.48 2 1.65 122 10.03 4 3.48 182 8.13
September 54 8.91 276 8.10 11 9.09 79 6.50 9 7.83 171 7.64
October 79 13.04 262 7.69 4 3.31 89 7.32 25 21.74 161 7.19
November 96 15.84 234 6.87 11 9.09 79 6.5 21 18.26 159 7.10
December 126 20.79 215 6.31 24 19.83 69 5.67 16 13.91 170 7.59
Precipitation N % N % N % N % N % N %
Days with precipitation 246 40.59 968 28.45 49 40.5 213 17.52 39 33.91 663 29.61
Wind Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD
Wind speed 9.36 3.54 7.62 3.16 12.49 4.62 10.68 4.31 10.03 3.36 8.71 3.21
  1. SD standard deviation
  2. aNon-referent days were used to generate the city-specific trees