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Table 3 Univariate analyses for acute chemical releases involving evacuations, by type of event.

From: Risk factors for acute chemical releases with public health consequences: Hazardous Substances Emergency Events Surveillance in the U.S., 1996–2001

Variable Fixed Facilities Transportation
  No. % with evac. POR (95% CI) No. % with evac. POR (95% CI)
Time of day       
   0000–0559 4130 6.5 referent 1237 4.9 referent
   0600–1159 10188 10.4 1.67 (1.45–1.92) 3085 5.1 1.04 (0.77–1.41)
   1200–1759 9363 10.2 1.64 (1.42–1.88) 2591 5.4 1.11 (0.82–1.51)
   1800–2359 5100 10.5 1.69 (1.45–1.97) 1210 6.1 1.26 (0.89–1.78)
Day of week       
   Weekend 5790 5.0 referent 1262 7.7 referent
   Weekday 24400 4.8 1.26 (1.14–1.40) 8170 8.8 0.95 (0.73–1.25)
Season       
   Dec.-Feb. 6683 9.2 referent 1682 5.4 referent
   Mar.-May 8058 9.6 1.04 (0.93–1.17) 2860 4.6 0.86 (0.65–1.13)
   Jun.-Aug. 8559 10.3 1.12 (1.01–1.25) 2849 4.7 0.87 (0.66–1.14)
   Sep.-Nov 6890 10.1 1.10 (0.98–1.23) 2041 4.8 0.89 (0.67–1.20)
Area*       
   Industrial 18958 8.5 0.60 (0.48–0.75) 2579 5.7 0.61 (0.43–0.85)
   Commercial 5438 5.2 3.11 (2.49–3.88) 3436 3.5 0.87 (0.63–1.19)
   Residential 2158 22.3 1.50 (1.38–1.62) 637 5.0 1.12 (0.98–1.28)
   Agricultural 2269 23.6 0.68 (0.51–0.89) 1681 7.9 0.86 (0.60–1.22)
   Other 1089 5.9 referent 947 4.9 referent
Release Type       
   Spill 11129 6.9 referent 7999 3.1 referent
   Air 17222 9.3 1.38 (1.27–1.51) 945 12.7 4.55 (3.61–5.72)
   Fire 869 35.7 7.48 (6.40–8.75) 134 20.2 7.89 (5.08–12.25)
   Explosion 242 36.8 7.85 (5.98–10.29) 10 20.0 7.81 (1.65–36.99)
   Fire & explosion 96 46.9 11.90 (7.92–17.89) 4 25.0 10.42 (1.08–100.5)
   Threatened 335 34.9 7.24 (5.72–9.17) 231 20.8 8.20 (5.82–11.54)
Substances†,‡
   Acid 1850 9.6 1.46 (1.27–1.67) NA
   Ammonia 2144 24.6 3.44 (3.09–3.83) 290 18.3 4.89 (3.57–6.69)
   Chlorine 599 33.1 4.79 (4.03–5.71) 22 27.3 7.52 (2.93–19.31)
   Multiple substances§ 1213 25.6 3.41 (2.98–3.90) 386 14.8 3.79 (2.81–5.10)
  1. *Type of general land use of the surrounding area in which the event occurred.
  2. Only substance categories with a 95% CI greater than 1.0 are presented.
  3. Substance categories were coded as yes/no. The referent group is all other substances.
  4. §Events with more than one hazardous substance released from different chemical categories.