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Correspondence |

Biomass Pollution, Chimney Stove Interventions, and Discrepant OutcomesBiomass Pollution and Chimneys FREE TO VIEW

Roberto A. Accinelli, MD; David Gozal, MD, FCCP
Author and Funding Information

From the Laboratorio de Respiración del Instituto de Investigaciones de la Altura (Dr Accinelli), Universidad Peruana Cayetano Heredia; and the Section of Pediatric Sleep Medicine (Dr Gozal), Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago.

CORRESPONDENCE TO: David Gozal, MD, FCCP, The University of Chicago, Knapp Center for Biomedical Discovery, Room 4100, 900 E 57th St, Mailbox 4, Chicago, IL 60637; e-mail: dgozal@peds.bsd.uchicago.edu


CONFLICT OF INTEREST: None declared.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2015;148(5):e163-e164. doi:10.1378/chest.15-1579
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Published online
To the Editor:

In the study by Guarnieri et al1 in this issue of CHEST (see page 1184), the authors reported no evidence for an association between lung function and early randomization to a chimney stove intervention. These findings prompted the authors to conclude that future studies may need to incorporate cleaner stoves or cleaner fuels.1 Personal carbon monoxide (CO) exposures in the chimney woodstoves used in their study were only reduced by 30% following stove installation, while other chimney stoves, such as Patsari (Grupo Interdisciplinario de Tecnología Rural Apropiada), reduce personal exposures to CO by 78%.2 Using the Patsari stove model, Romieu et al3 reported a significantly lower FEV1 decline (31 mL) compared with open fire use (62 mL) over 1 year of follow-up (P = .012) for women 20 years of age and older. Zhou et al4 found less deterioration in FEV1 of 12, 13, and 16 mL/y in those who used biogas, improved ventilation, or both, respectively, compared with those who took up neither intervention, after adjustment for confounders. The longer the duration of improved fuel use and ventilation, the greater the benefits in slowing the decline of FEV1 (P < .05).4

The question, then, is why the discrepant findings? We should point out that a chimney does not guarantee less indoor pollution. Indeed, chimneys did not significantly reduce median concentrations in 24-h, indoor fine particulate matter (PM2.5) (119 μg/m3 vs 137 μg/m3; P = .40) or CO (4.6 parts per million vs 7.2 parts per million; P = .23) among rural households with and without chimneys.5 Hartinger et al6 found that PM2.5 and CO measurements did not differ significantly between optimally improved stoves and traditional biomass stoves. Guarnieri et al1 concluded it was necessary to incorporate cleaner stoves in future studies.

We suggest that the methodologic approach may account for the discrepant findings related to chimney/stove interventions. In the study by Guarnieri et al1 inclusion criteria for the families were exclusive use of an open fire for cooking and heating and the presence of a pregnant woman or an infant < 4 months of age. The eligible households were randomly allocated to either chimney woodstoves or to continue with traditional ones.1 With the chimney woodstoves, the mean CO concentrations in the kitchen were lowered by about 90%, child exposures were lowered by only 50%, and mothers’ exposures by only 30%.1 The different results across different subjects and locations have been previously attributed to venting smoke, which reenters the homes and generally contaminates both outdoor and indoor environments where children spend some of their time.7 Cynthia et al2 found, in a randomized intervention with Patsari stoves, a reduction of PM2.5 in the kitchen of 74% and in women, only 35%. We propose that the marked differences between exposure levels are because, in the context of random allocation of chimney stoves, people with improved stoves will continue visiting houses with traditional stoves. This pattern is further enhanced among pregnant women and those with young children, who will visit frequently and for long periods of time their mothers and relatives for help and support in their daily labors. Hence, the impact of chimneys or stoves may be markedly diminished by the social interactions in the villages receiving the research intervention.

Thus, Guarnieri et al1 provide excellent evidence attesting to the necessity of installing the best-designed chimney stoves. In Peru, allocation of public resources to support environmental measures requires placement of certified stoves that reduce at least 90% of pollutants inside the kitchen. However, to conduct an intervention that will effectively reduce indoor pollution, it is mandatory to change all the stoves of a given community, such that for research-based interventions, we need to use communities as the measurement unit rather than families.

References

Guarnieri M, Diaz E, Pope D, et al. Lung function in rural Guatemalan women before and after a chimney stove intervention to reduce woodsmoke exposure: results from the Randomized Exposure Study of Pollution Indoors and Respiratory Effects and Chronic Respiratory Effects of Early Childhood Exposure to Respirable Particulate Matter Study. Chest. 2015;148(5):1184-1192.
 
Cynthia AA, Edwards RD, Johnson M, et al. Reduction in personal exposures to particulate matter and carbon monoxide as a result of the installation of a Patsari improved cook stove in Michoacan Mexico. Indoor Air. 2008;18(2):93-105. [CrossRef] [PubMed]
 
Romieu I, Riojas-Rodríguez H, Marrón-Mares AT, Schilmann A, Perez-Padilla R, Masera O. Improved biomass stove intervention in rural Mexico: impact on the respiratory health of women. Am J Respir Crit Care Med. 2009;180(7):649-656. [CrossRef] [PubMed]
 
Zhou Y, Zou Y, Li X, et al. Lung function and incidence of chronic obstructive pulmonary disease after improved cooking fuels and kitchen ventilation: a 9-year prospective cohort study. PLoS Med. 2014;11(3):e1001621. [CrossRef] [PubMed]
 
Pollard SL, Williams DL, Breysse PN, et al; CRONICAS Cohort Study Group. A cross-sectional study of determinants of indoor environmental exposures in households with and without chronic exposure to biomass fuel smoke. Environ Health. 2014;13(1):21. [CrossRef] [PubMed]
 
Hartinger SM, Commodore AA, Hattendorf J, et al. Chimney stoves modestly improved indoor air quality measurements compared with traditional open fire stoves: results from a small-scale intervention study in rural Peru. Indoor Air. 2013;23(4):342-352. [CrossRef] [PubMed]
 
Smith-Sivertsen T, Díaz E, Pope D, et al. Effect of reducing indoor air pollution on women’s respiratory symptoms and lung function: the RESPIRE Randomized Trial, Guatemala. Am J Epidemiol. 2009;170(2):211-220. [CrossRef] [PubMed]
 

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References

Guarnieri M, Diaz E, Pope D, et al. Lung function in rural Guatemalan women before and after a chimney stove intervention to reduce woodsmoke exposure: results from the Randomized Exposure Study of Pollution Indoors and Respiratory Effects and Chronic Respiratory Effects of Early Childhood Exposure to Respirable Particulate Matter Study. Chest. 2015;148(5):1184-1192.
 
Cynthia AA, Edwards RD, Johnson M, et al. Reduction in personal exposures to particulate matter and carbon monoxide as a result of the installation of a Patsari improved cook stove in Michoacan Mexico. Indoor Air. 2008;18(2):93-105. [CrossRef] [PubMed]
 
Romieu I, Riojas-Rodríguez H, Marrón-Mares AT, Schilmann A, Perez-Padilla R, Masera O. Improved biomass stove intervention in rural Mexico: impact on the respiratory health of women. Am J Respir Crit Care Med. 2009;180(7):649-656. [CrossRef] [PubMed]
 
Zhou Y, Zou Y, Li X, et al. Lung function and incidence of chronic obstructive pulmonary disease after improved cooking fuels and kitchen ventilation: a 9-year prospective cohort study. PLoS Med. 2014;11(3):e1001621. [CrossRef] [PubMed]
 
Pollard SL, Williams DL, Breysse PN, et al; CRONICAS Cohort Study Group. A cross-sectional study of determinants of indoor environmental exposures in households with and without chronic exposure to biomass fuel smoke. Environ Health. 2014;13(1):21. [CrossRef] [PubMed]
 
Hartinger SM, Commodore AA, Hattendorf J, et al. Chimney stoves modestly improved indoor air quality measurements compared with traditional open fire stoves: results from a small-scale intervention study in rural Peru. Indoor Air. 2013;23(4):342-352. [CrossRef] [PubMed]
 
Smith-Sivertsen T, Díaz E, Pope D, et al. Effect of reducing indoor air pollution on women’s respiratory symptoms and lung function: the RESPIRE Randomized Trial, Guatemala. Am J Epidemiol. 2009;170(2):211-220. [CrossRef] [PubMed]
 
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