title: Sustained use of biogas fuel and blood pressure among women in rural Nepal.
abstract: BACKGROUND
  More than two fifths of the world's population cook with solid fuels and are exposed to household air pollution (HAP). As of now, no studies have assessed whether switching to alternative fuels like biogas could impact cardiovascular health among cooks previously exposed to solid fuel use.
  
  
  METHODS
  We conducted a propensity score matched cross-sectional study to explore if the sustained use of biogas fuel for at least ten years impacts blood pressure among adult female cooks of rural Nepal. We recruited one primary cook ≥ 30 years of age from each biogas (219 cooks) and firewood (300 cooks) using household and measured their systolic (SBP) and diastolic blood pressure (DBP). Household characteristics, kitchen ventilation and 24-h kitchen carbon monoxide were assessed. We matched cooks by age, body mass index and socio-economic status score using propensity scores and investigated the effect of biogas use through multivariate regression models in two age groups, 30-50 years and >50 years to account for any post-menopausal changes.
  
  
  RESULTS
  We found substantially reduced 24-h kitchen carbon monoxide levels among biogas-using households. After matching and adjustment for smoking, kitchen characteristics, ventilation status and additional fuel use, the use of biogas was associated with 9.8 mmHg lower SBP [95% confidence interval (CI), -20.4 to 0.8] and 6.5 mmHg lower DBP (95% CI, -12.2 to -0.8) compared to firewood users among women >50 years of age. In this age group, biogas use was also associated with 68% reduced odds [Odds ratio 0.32 (95% CI, 0.14 to 0.71)] of developing hypertension. These effects, however, were not identified in younger women aged 30-50 years.
  
  
  CONCLUSIONS
  Sustained use of biogas for cooking may protect against cardiovascular disease by lowering the risk of high blood pressure, especially DBP, among older female cooks. These findings need to be confirmed in longitudinal or experimental studies.
authors.affiliation: Center for International Health, Ludwig-Maximilians-Universitaet, Munich, Germany; Mountain Medicine Society of Nepal, Kathmandu, Nepal. Electronic address: maniraj.neupane@gmail.com.
authors.forename: Maniraj
authors.initials: M
authors.lastname: Neupane
authors.affiliation: Oxford University Clinical Research Unit, Patan Hospital, Kathmandu, Nepal.
authors.forename: Buddha
authors.initials: B
authors.lastname: Basnyat
authors.affiliation: Center for International Health, Ludwig-Maximilians-Universitaet, Munich, Germany.
authors.forename: Rainald
authors.initials: R
authors.lastname: Fischer
authors.affiliation: Center for International Health, Ludwig-Maximilians-Universitaet, Munich, Germany.
authors.forename: Guenter
authors.initials: G
authors.lastname: Froeschl
authors.affiliation: The Hospital for Tropical Disease, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit-Vietnam, Ho Chi Minh City, Vietnam.
authors.forename: Marcel
authors.initials: M
authors.lastname: Wolbers
authors.affiliation: Institute for Medical Informatics, Biometry and Epidemiology, Ludwig-Maximilians-Universitaet, Munich, Germany.
authors.forename: Eva A
authors.initials: EA
authors.lastname: Rehfuess
mesh_terms: D056804:Biofuels; D001794:Blood Pressure; D003296:Cooking; D005260:Female; D006801:Humans; D009390:Nepal; D009790:Occupations; D012424:Rural Population
chemical_list: D056804:Biofuels
keywords: Biogas; Blood pressure; Cardiovascular disease; Household air pollution; Nepal