Effect of reducing indoor air pollution on women's respiratory symptoms and lung function: the RESPIRE Randomized Trial, Guatemala

Abstract

Exposure to household wood smoke from cooking is a risk factor for chronic obstructive lung disease among women in developing countries. The Randomized Exposure Study of Pollution Indoors and Respiratory Effects (RESPIRE) is a randomized intervention trial evaluating the respiratory health effects of reducing indoor air pollution from open cooking fires. A total of 504 rural Mayan women in highland Guatemala aged 15-50 years, all using traditional indoor open fires, were randomized to either receive a chimney woodstove (plancha) or continue using the open fire. Assessments of chronic respiratory symptoms and lung function and individual measurements of carbon monoxide exposure were performed at baseline and every 6 months up to 18 months. Use of a plancha significantly reduced carbon monoxide exposure by 61.6%. For all respiratory symptoms, reductions in risk were observed in the plancha group during follow-up; the reduction was statistically significant for wheeze (relative risk = 0.42, 95% confidence interval: 0.25, 0.70). The number of respiratory symptoms reported by the women at each follow-up point was also significantly reduced by the plancha (odds ratio = 0.7, 95% confidence interval: 0.50, 0.97). However, no significant effects on lung function were found after 12-18 months. Reducing indoor air pollution from household biomass burning may relieve symptoms consistent with chronic respiratory tract irritation.

Figures

Figure 1.

Distribution of the study population from baseline through follow-up, San Marcos, Guatemala, 2002–2003. OF, open fire; P, plancha.

Figure 2.

Median 48-hour personal exposure to carbon monoxide, by intervention status (plancha vs. open fire), San Marcos, Guatemala, 2002–2004. Carbon monoxide levels were measured by means of passive diffusion tubes. Postintervention data represent the average of all postintervention measurements. Outliers were excluded. Bars, interquartile range (25th–75th percentile).

Figure 3.

Prevalences of phlegm (part A) and cough (part B) in the intervention (plancha) and control (open fire) groups from baseline to 18 months, recruitment group B, San Marcos, Guatemala, 2002–2004. For questions, see Appendix 1. Bars, 95% confidence interval.

Figure 4.

Relative risk of respiratory symptoms in the intervention group (women who received a plancha), San Marcos, Guatemala, 2002–2004. Relative risks were derived using generalized estimating equations. For each symptom, the solid line represents all postintervention assessments and the dashed line represents only the 12- and 18-month assessments. For questions and definitions, see Appendix 2. Bars, 95% confidence interval.