Adjusted relative percentage changes (95% CI), relative to subject mean, in PEF and FEV1 by heater type
| Same day | Lag 1 | |||
| Evening | Change morning–evening | Morning | Evening | |
| PEF | ||||
| Days UFGH versus other heater used | 0.71 (−0.19 to 1.61) | −1.13 (−2.15 to −0.12)* | −0.36 (−1.28 to 0.56) | −0.09 (−0.99 to 0.82) |
| Days UFGH used versus no heating | −0.50 (−1.39 to 0.38) | −2.53 (−3.58 to −1.49)* | −0.22 (−1.13 to 0.68) | 0.14 (−0.77 to 1.06) |
| Days other heater used versus no heating | −1.21 (−1.79 to 0.45) | −0.78 (−1.76 to 0.20) | −0.38 (−1.16 to 0.41) | 0.08 (−0.69 to 0.85) |
| FEV1 | ||||
| Days UFGH versus other heater used | 0.43 (−0.53 to 1.38) | −0.92 (−1.98 to 0.14) | 0.27 (−0.71 to 1.26) | −0.02 (−0.96 to 0.92) |
| Days UFGH used versus no heating | −0.31 (−1.24 to 0.63) | −1.77 (−2.82 to −0.71)* | −0.24 (−1.18 to 0.69) | −0.34 (−1.27 to 0.60) |
| Days other heater used versus no heating | −1.14 (−2.04 to 0.24) | 0.84 (−1.90 to 0.22) | −0.27 (−1.20 to 0.65) | −0.18 (−1.09 to 0.73) |
Adjusted for age, gender, exposure to tobacco smoke, exposure to cooking gas, ambient temperature, humidity and external NO2 levels.
↵* Significant finding (p<0.05).
UFGH, unflued gas heater; FEV1, forced expiratory volume in 1 s; PEF, peak expiratory flow.