Table 3

Mixed effects model analysis of PM2.5, using natural log-transformed data based on 10 s average raw data, Toronto Doorway Study, May to June 2008

Adjusted analysis
OutdoorIndoor*
Coefficient (95% CI)p ValueCoefficient (95% CI)p Value
Model 1
 Background
 Outdoor or indoor
Model 2
 0 lit cigarettesReferenceReference
 1 or more lit cigarettes0.54 (0.38 to 0.71)<0.00010.06 (−0.03 to 0.15)0.2072
Model 3
 0 lit cigarettesReferenceReference
 1–4 lit cigarettes0.49 (0.33 to 0.66)<0.00010.06 (−0.03 to 0.15)0.2181
 5 or more lit cigarettes0.85 (0.61 to 1.10)<0.00010.07 (−0.07 to 0.22)0.3287
Model 4
 Linear trend of lit cigarettes§0.10 (0.07 to 0.14)<0.00010.0002 (−0.02 to 0.02)0.9853
Model 5
 Indoor PM2.5 by outdoor PM2.50.04 (0.01 to 0.07)0.0046
  • * Lit cigarettes for indoor measures meant smoking outside the entrance while measuring PM2.5 inside the entrance.

  • Outdoor measures adjusted for: wind strength and direction, distance to nearest lit cigarette from the monitor.

  • Indoor measures adjusted for: distance from nearest lit cigarette to entrance, distance from indoor monitor to entrance, number of door openings, as well as outdoor wind direction and strength.

  • § Actual number of lit cigarettes was entered into the mixed model so that the coefficient indicated the log PM2.5 level increased by each 1 lit cigarette increase.

  • No wind measures and distance to nearest lit cigarette from the monitor were taken for background measures.

  • PM2.5, air pollutant particles with a diameter of 2.5 μm or less.