title: Control of household air pollution for child survival: estimates for intervention impacts.
abstract: BACKGROUND
  Exposure to household air pollution (HAP) from cooking with solid fuels affects 2.8 billion people in developing countries, including children and pregnant women. The aim of this review is to propose intervention estimates for child survival outcomes linked to HAP.
  
  
  METHODS
  Systematic reviews with meta-analysis were conducted for ages 0-59 months, for child pneumonia, adverse pregnancy outcomes, stunting and all-cause mortality. Evidence for each outcome was assessed against Bradford-Hill viewpoints, and GRADE used for certainty about intervention effect size for which all odds ratios (OR) are presented as protective effects.
  
  
  RESULTS
  Reviews found evidence linking HAP exposure with child ALRI, low birth weight (LBW), stillbirth, preterm birth, stunting and all-cause mortality. Most studies were observational and rated low/very low in GRADE despite strong causal evidence for some outcomes; only one randomised trial was eligible.Intervention effect (OR) estimates of 0.64 (95% CI: 0.55, 0.75) for ALRI, 0.71 (0.65, 0.79) for LBW and 0.66 (0.54, 0.81) for stillbirth are proposed, specific outcomes for which causal evidence was sufficient. Exposure-response evidence suggests this is a conservative estimate for ALRI risk reduction expected with sustained, low exposure. Statistically significant protective ORs were also found for stunting [OR=0.79 (0.70, 0.89)], and in one study of pre-term birth [OR=0.70 (0.54, 0.90)], indicating these outcomes would also likely be reduced. Five studies of all-cause mortality had an OR of 0.79 (0.70, 0.89), but heterogenity precludes a reliable estimate for mortality impact. Although interventions including clean fuels and improved solid fuel stoves are available and can deliver low exposure levels, significant challenges remain in achieving sustained use at scale among low-income households.
  
  
  CONCLUSIONS
  Reducing exposure to HAP could substantially reduce the risk of several child survival outcomes, including fatal pneumonia, and the proposed effects could be achieved by interventions delivering low exposures. Larger impacts are anticipated if WHO air quality guidelines are met. To achieve these benefits, clean fuels should be adopted where possible, and for other households the most effective solid fuel stoves promoted. To strengthen evidence, new studies with thorough exposure assessment are required, along with evaluation of the longer-term acceptance and impacts of interventions.
authors.forename: Nigel G
authors.initials: NG
authors.lastname: Bruce
authors.forename: Mukesh K
authors.initials: MK
authors.lastname: Dherani
authors.forename: Jai K
authors.initials: JK
authors.lastname: Das
authors.forename: Kalpana
authors.initials: K
authors.lastname: Balakrishnan
authors.forename: Heather
authors.initials: H
authors.lastname: Adair-Rohani
authors.forename: Zulfiqar A
authors.initials: ZA
authors.lastname: Bhutta
authors.forename: Dan
authors.initials: D
authors.lastname: Pope
mesh_terms: D000328:Adult; D016902:Air Pollution, Indoor / Q000009:adverse effects / Q000517:prevention & control* / Q000706:statistics & numerical data; D002648:Child; D002669:Child Welfare / Q000706:statistics & numerical data*; D003296:Cooking; D003906:Developing Countries; D004781:Environmental Exposure / Q000009:adverse effects / Q000517:prevention & control* / Q000706:statistics & numerical data; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D019570:Inhalation Exposure / Q000009:adverse effects / Q000517:prevention & control* / Q000706:statistics & numerical data; D011247:Pregnancy; D012140:Respiratory Tract Diseases / Q000453:epidemiology* / Q000517:prevention & control; D012307:Risk Factors; D012720:Severity of Illness Index