Intervention | Control | Intervention versus control | P value | |

FEV_{1}, mean (SD) L* | 1.02 (0.18) | 0.97 (0.19) | 0.02 (−0.01 to 0.06) | 0.135 |

FVC, mean (SD) L* | 1.16 (0.21) | 1.09 (0.21) | 0.04 (0.00 to 0.07) | 0.033 |

FEV_{1}/FVC, mean (SD) * | 0.88 (0.06) | 0.89 (0.06) | −0.01 (−0.02 to 0.01) | 0.411 |

%COHb, median (IQR)†‡ | 3.50 (1.00 to 6.00) | 4.85 (2.00 to 7.00) | −0.89 (−1.53 to −0.26) | 0.006 |

Mean CO ppm, median (IQR)§‡¶** | 0.18 (0.05 to 0.55) | 0.20 (0.08 to 0.52) | 0.03 (−0.35 to 0.42) | 0.857 |

Weight-for-age z-score, mean (SD)† | −1.20 (0.89) | −1.06 (0.85) | −0.13 (−0.29 to 0.02) | 0.096 |

Height-for-age z-score, mean (SD)† | −1.10 (0.84) | −1.06 (0.93) | −0.04 (−0.20 to 0.12) | 0.624 |

MUAC, mean (SD) cm†† | 15.92 (1.29) | 15.94 (1.30) | −0.02 (−0.26 to 0.21) | 0.846 |

*Spirometry data for 300 participants; 167 intervention, 133 control. FEV

_{1}, FVC and FEV_{1}/FVC adjusted for age, sex, height and weight in regression model.†COHb, height and weight data for 476 participants; 260 intervention, 216 control.

‡Adjusted for seasonality in linear regression model.

§24 hours CO monitoring for 436 participants; 239 intervention, 197 control.

¶Log

_{10}CO values used in linear regression model.**Mean exposure was estimated over the monitoring period per individual, the median of these values (and IQR) is presented for the study population.

††MUAC for 466 participants; 260 intervention, 206 control.

CO, carbon monoxide; COHb, carboxyhaemoglobin level; FEV

_{1}, forced expiratory volume in one second; FVC, forced vital capacity; MUAC, mid-upper arm circumference.