Table 4. Associations between Ln-transformed maximum ozone concentration and reported symptoms by stepwise logistic regression.
| Dependent variable | N | aOR a (ozone) | 95% CI (ozone) | p-value (ozone) | Flight related variables in the final model b |
|---|---|---|---|---|---|
| Dry mouth or lips | 4018 | 1.14 | 1.05–1.24 | 0.002 | RH, occupancy, airline(3.OR>1), duration |
| Dry eyes | 3940 | 1.08 | 0.96–1.21 | 0.20 | RH(OR>1), Qpers, occupancy(OR<1), airline(2,3.OR>1), duration(2.OR>1), aircraft(2,3,4,5.OR>1) |
| Nasal stuffiness | 3981 | 1.13 | 1.00–1.28 | 0.055 | T(OR<1), pressure, Qpers(OR<1), occupancy(OR<1), airline(2,3.OR>1), duration(2.OR>1), aircraft |
| Itchy eyes | 4053 | 1.16 | 1.04–1.29 | 0.008 | - |
| Dry, irritated or sore throat | 3973 | NS | - | - | duration(3.OR>1) |
| Runny nose or sneezing | 3971 | NS | - | - | T(OR<1), duration(3.OR>0) |
| Headaches | 4053 | NS | - | - | pressure, duration, aircraft |
| Cough | 4078 | NS | - | - | airline |
| Watery eyes | 4158 | NS | - | - | T(OR<1), airline(3.OR>0) |
| Blurred, dim, altered vision | 3995 | NS | - | - | RH(OR>0), Qpers(OR>1), airline |
| Hoarseness/loss of voice | 3964 | 1.29 | 0.96–1.72 | 0.09 | occupancy |
| Lightheaded, dizzy or faint | 3973 | 1.24 | 0.92–1.69 | 0.16 | RH(OR>1), pressure, Qpers |
| Eye pain | 3998 | NS | - | - | T, RH(OR<1), aircraft(4,5.OR>1) |
| Any eye, mouth symptom | 3940 | 1.16 | 1.07–1.26 | 0.000 | T(OR<1), RH(OR>1), pressure(OR>1), Qpers(OR<1), occupancy(OR<1), airline(3.OR>1), duration(2,3.OR>1) |
| Any muscular symptom | 3981 | NS | - | - | pressure, Qpers(OR<1), occupancy(OR<1), airline(2.OR>1), duration(2,3.OR>1), aircraft(2.OR>1) |
| Any upper resp. symptom | 3940 | 1.03 | 0.93–1.14 | 0.55 | T(OR<1), pressure, Qpers, occupancy(OR<1), airline(2,3.OR>1), duration(2.OR>1), aircraft |
| Any ear, head symptom | 3971 | NS | - | - | T(OR<1), RH, aircraft(2,3,4,5.OR<1) |
| Any digestive symptom | 4060 | NS | - | - | T, pressure, occupancy(OR<1), airline, duration(3.OR>1) |
| Any neurol. symptom | 4041 | 0.94 | 0.79–1.11 | 0.46 | pressure, Qpers, airline(3.OR>1), aircraft(4.OR>1) |
| Any lower resp. symptom | 4158 | NS | - | - | RH |
For all models R2<0.1, p<0.05, except Itchy eyes, p = 0.06; Cough, p = 0.12; Watery eyes, p = 0.09; Hoarseness/loss of voice, p = 0.14; Any lower resp. symptom, p = 0.18
a NS—not selected by the stepwise backward variable selection
b The flight-related variables that were included in the final model based on a significance level of p<0.2 for removal from the model (stepwise backwards variable selection [41]). In parentheses the directions of the ORs for the variables (continuous) or their categories (categorical) are indicated when significant at p<0.05.