Using exhaled carbon monoxide and carboxy-hemoglobin to evaluate the effectiveness of a chimney stove model in Peru

Abstract

Background: Measurement of biological indicators of physiological change may be useful in evaluating the effectiveness of stove models, which are intended to reduce indoor smoke exposure and potential health effects.

Objectives: We examined changes in exhaled carbon monoxide (CO), percentage carboxy-hemoglobin, and total hemoglobin in response to the installation of a chimney stove model by the Juntos National Program in Huayatan, Peru in 2008.

Methods: Biomarkers were measured in a convenience sample comprising 35 women who met requirements for participation, and were measured before and three weeks after installation of a chimney stove. The relationships between exposure to indoor smoke and biomarker measurements were also analyzed using simple linear regression models.

Results: Exhaled CO reduced from 6·71 ppm (95% CI 5·84–7·71) to 3·14 ppm (95% CI 2·77–3·66) three weeks after stove installation (P < 0·001) while % COHb reduced from 1·76% (95% CI 1·62–1·91) to 1·18% (95% CI 1·12–1·25; P < 0·001). Changes in exhaled CO and % COHb from pre- to post-chimney stove installation were not correlated with corresponding changes in exposure to CO and PM_2·5 even though the exposures also reduced after stove installation.

Conclusion: Exhaled CO and % COHb both showed improvement with reduction in concentration after the installation of the chimney cook stoves, indicating a positive physiological response subsequent to the intervention.

Keywords:

• Biomass
• Indoor air pollution
• Exhaled CO
• Percentage carboxy-hemoglobin (% COHb)
• Total blood hemoglobin concentration (Hb)
• Peru

We would like to thank the subjects, without whom this study could not be done. We thank Barrick Gold Corporation, who voluntarily funded this study under an agreement with the Gobierno Regional de la Libertad – particulary: Carlos Cabanillas Bustamante, Guillermo Manrique Franco, Alejandro Sanchez, and Dr. Luis Perez Villasante. Other supporters included: Jose Murgia Zanier, President of the Regional Government of La Libertad, Dr. Pedro Diaz Camacho from the regional Government of La Libertad, Professor Abner Avalos Villacorta, then Mayor of Santiago de Chuco, and Dr. Alipio Mantilla Linares, Director of the Hospital in Santiago de Chuco. We also acknowledge coVita (Haddonfield, NJ, USA) and NIR Diagnostics (Capbellville ON, Canada) who loaned the Pico+ exhaled CO sensor and the total hemoglobin HemoNIR device, respectively, to our lab for this study.