| Chimney Stove Intervention to Reduce Long-term Wood Smoke Exposure Lowers Blood Pressure among Guatemalan Women John P. McCracken,1,2 Kirk R. Smith,3 Anaité Díaz,4 Murray A. Mittleman,1,5 and Joel Schwartz1,2 1Department of Epidemiology, and 2Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; 3Environmental Health Sciences Division, School of Public Health, University of California, Berkeley, California, USA; 4Center for Health Studies, Universidad del Valle, Guatemala City, Guatemala; 5Cardiovascular Epidemiology Research Unit, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA Abstract
Background and Objective: RESPIRE, a randomized trial of an improved cookstove, was conducted in Guatemala to assess health effects of long-term reductions in wood smoke exposure. Given the evidence that ambient particles increase blood pressure, we hypothesized that the intervention would lower blood pressure. Methods: Two study designs were used: a) between-group comparisons based on randomized stove assignment, and b) before-and-after comparisons within subjects before and after they received improved stoves. From 2003 to 2005, we measured personal fine particle (particulate matter with aerodynamic diameter < 2.5 µm ; PM2.5) exposures and systolic (SBP) and diastolic blood pressure (DBP) among women > 38 years of age from the chimney woodstove intervention group (49 subjects) and traditional open wood fire control group (71 subjects) . Measures were repeated up to three occasions. Results: Daily average PM2.5 exposures were 264 and 102 µg/m3 in the control and intervention groups, respectively. After adjusting for age, body mass index, an asset index, smoking, secondhand tobacco smoke, apparent temperature, season, day of week, time of day, and a random subject intercept, the improved stove intervention was associated with 3.7 mm Hg lower SBP [95% confidence interval (CI) , –8.1 to 0.6] and 3.0 mm Hg lower DBP (95% CI, –5.7 to –0.4) compared with controls. In the second study design, among 55 control subjects measured both before and after receiving chimney stoves, similar associations were observed. Conclusion: The between-group comparisons provide evidence, particularly for DBP, that the chimney stove reduces blood pressure, and the before-and-after comparisons are consistent with this evidence. Key words: biomass fuel, cardiovascular disease, echo-intervention, indoor air pollution, RESPIRE project. Environ Health Perspect 115:996–1001 (2007) . doi:10.1289/ehp.9888 available via http://dx.doi.org/ [Online 14 February 2007]
Address correspondence to J.P. McCracken, Department of Environmental Health, Harvard School of Public Health, Landmark Building, 415 West, 401 Park Dr., Boston, MA 02215 USA. Telephone: (617) 384-8754. Fax: (617) 384-8745. E-mail: jmccrack@hsph.harvard.edu We are grateful to B. Arana and R. Acevedo of the Universidad del Valle for help in coordinating the field research and data management. We appreciate the dedication of the local fieldworkers and thank the Guatemalan Ministry of Health for use of their clinic. RESPIRE was funded by the National Institute of Environmental Health Sciences (NIEHS) (R01ES010178) , the World Health Organization, and the AC Griffin Family Trust. This cardiovascular component was funded by NIEHS (ES-0002) , U.S. Environmental Protection Agency PM Center (R 827353) , NIEHS (P01-ES09825) , and NIEHS (T-32 ES07069-25) . The authors declare they have no competing financial interests. Received 7 November 2006 ; accepted 14 February 2007.
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