Pneumonia and Exposure to Household Air Pollution in Children Under the Age of 5 Years in Rural Malawi

Abstract

BackgroundExposure to household air pollution is associated with an increased risk of pneumonia in children in low- and middle-income countries; however, exposure-response data are limited, and there are uncertainties around the extent to which biomass-fueled cookstoves can reduce these exposures.Research QuestionWhat is the association between exposure to household air pollution and pneumonia in children under the age of 5 years in rural Malawi and what are the effects of a biomass-fueled cookstove intervention on personal exposure to household air pollution?Study Design and MethodsWe measured personal exposure to carbon monoxide (CO; 48 hours of continuous measurement and transcutaneous carboxyhemoglobin) every 6 months in children who participated in a cluster-randomized controlled trial of a cleaner burning biomass-fueled cookstove intervention to prevent pneumonia in children under the age of 5 years in rural Malawi (the Cooking And Pneumonia Study). Exposure-response and multivariable analyses were done.ResultsWe recruited 1805 (928 intervention; 877 control) children (mean age, 25.6 months; 50.6% female). We found no evidence of an association between exposure to CO (incident rate ratio, 1.0; 95% CI, 0.967 to 1.014; P = .53) or carboxyhemoglobin (incident rate ratio, 1.00; 95% CI, 0.993 to 1.003; P = .41) in children who experienced pneumonia vs those who did not. Median exposure to CO in the intervention and control groups was was 0.34 (interquartile range, 0.15 to 0.81) and 0.37 parts per million (interquartile range, 0.15 toa 0.97), respectively. The group difference in means was 0.46 (95% CI, −0.95 to 0.012; P = .06).InterpretationExposure to CO in our population was low with no association seen between exposure to CO and pneumonia incidence and no effect of the Cooking And Pneumonia Study intervention on these exposures. These findings suggest that CO may not be an appropriate measure of household air pollution exposure in settings such as rural Malawi and that there is a need to develop ways to measure particulate matter exposures directly in young children instead.Clinical Trial RegistrationISRCTN59448623. Exposure to household air pollution is associated with an increased risk of pneumonia in children in low- and middle-income countries; however, exposure-response data are limited, and there are uncertainties around the extent to which biomass-fueled cookstoves can reduce these exposures. What is the association between exposure to household air pollution and pneumonia in children under the age of 5 years in rural Malawi and what are the effects of a biomass-fueled cookstove intervention on personal exposure to household air pollution? We measured personal exposure to carbon monoxide (CO; 48 hours of continuous measurement and transcutaneous carboxyhemoglobin) every 6 months in children who participated in a cluster-randomized controlled trial of a cleaner burning biomass-fueled cookstove intervention to prevent pneumonia in children under the age of 5 years in rural Malawi (the Cooking And Pneumonia Study). Exposure-response and multivariable analyses were done. We recruited 1805 (928 intervention; 877 control) children (mean age, 25.6 months; 50.6% female). We found no evidence of an association between exposure to CO (incident rate ratio, 1.0; 95% CI, 0.967 to 1.014; P = .53) or carboxyhemoglobin (incident rate ratio, 1.00; 95% CI, 0.993 to 1.003; P = .41) in children who experienced pneumonia vs those who did not. Median exposure to CO in the intervention and control groups was was 0.34 (interquartile range, 0.15 to 0.81) and 0.37 parts per million (interquartile range, 0.15 toa 0.97), respectively. The group difference in means was 0.46 (95% CI, −0.95 to 0.012; P = .06). Exposure to CO in our population was low with no association seen between exposure to CO and pneumonia incidence and no effect of the Cooking And Pneumonia Study intervention on these exposures. These findings suggest that CO may not be an appropriate measure of household air pollution exposure in settings such as rural Malawi and that there is a need to develop ways to measure particulate matter exposures directly in young children instead. ISRCTN59448623. Malawi has one of the world’s highest infant and <5-year-old children mortality rates (42 and 63 per 1000 live births, respectively, in 2015 to 2016) despite having made progress towards meeting the Millennium Development Goal of reducing child mortality rates.1https://dhsprogram.com/publications/publication-FR319-DHS-Final-Reports.cfmGoogle Scholar Pneumonia is the leading cause of death and one of the most common causes of morbidity.2Liu L. Johnson H.L. Cousens S. et al.(2012) Global, regional, and national causes of child mortality: an updated systematic analysis for 2010 with time trends since 2000.Lancet. 2012; 379: 2151-2161Abstract Full Text Full Text PDF PubMed Scopus (2490) Google Scholar,3Harris C. Mills R. Seager E. et al.Paediatric deaths in a tertiary government hospital setting, Malawi.Paediatr Int Child Health. 2018; : 1-9PubMed Google ScholarTake-home PointStudy question: What is the association between exposure to household air pollution and pneumonia in children under the age of 5 years in rural Malawi, and what are the effects of a biomass-fueled cookstove intervention on personal exposure to household air pollution?Results: Exposure to carbon monoxide in our population was low with no association seen between exposure to carbon monoxide and pneumonia incidence and no effect of a biomass-fueled cookstove intervention on these exposures.Interpretation: Carbon monoxide may not be an appropriate measure of household air pollution exposure in settings like rural Malawi. The role of cleaner-burning cookstoves and fuels as standalone health interventions needs to be reexamined. Study question: What is the association between exposure to household air pollution and pneumonia in children under the age of 5 years in rural Malawi, and what are the effects of a biomass-fueled cookstove intervention on personal exposure to household air pollution? Results: Exposure to carbon monoxide in our population was low with no association seen between exposure to carbon monoxide and pneumonia incidence and no effect of a biomass-fueled cookstove intervention on these exposures. Interpretation: Carbon monoxide may not be an appropriate measure of household air pollution exposure in settings like rural Malawi. The role of cleaner-burning cookstoves and fuels as standalone health interventions needs to be reexamined. Exposure to smoke produced when biomass fuels (animal or plant material) are burned in open fires is understood to be a major avoidable risk factor for pneumonia in young children.4World Health Organization 2014Indoor air quality guidelines: household fuel combustion.http://apps.who.int/iris/bitstream/10665/141496/1/9789241548885_eng.pdfGoogle Scholar, 5Gordon S.B. Bruce N.G. Grigg J. et al.Respiratory risks form household air pollution in low and middle income countries.Lancet Respir Med. 2014; 2: 823-860Abstract Full Text Full Text PDF PubMed Scopus (469) Google Scholar, 6Mortimer K. Gordon S.B. Jindal S.K. Accinelli R.A. Balmes J. Martin II, W.J. Household air pollution is a major avoidable risk factor for cardio-respiratory disease.Chest. 2012; 142: 1308-1315Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar In Africa, biomass fuels are used widely to provide energy for cooking, heating, and lighting. Women and young children experience high levels of smoke exposure when meals are cooked over open fires due to partial combustion of fuel and poor ventilation.5Gordon S.B. Bruce N.G. Grigg J. et al.Respiratory risks form household air pollution in low and middle income countries.Lancet Respir Med. 2014; 2: 823-860Abstract Full Text Full Text PDF PubMed Scopus (469) Google Scholar,6Mortimer K. Gordon S.B. Jindal S.K. Accinelli R.A. Balmes J. Martin II, W.J. Household air pollution is a major avoidable risk factor for cardio-respiratory disease.Chest. 2012; 142: 1308-1315Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar Household air pollution from open fires is a major threat to health, ranking 10th in the World Health Organization (WHO) comparative risk assessment for the global burden of disease.7http://www.who.int/healthinfo/global_burden_disease/GlobalHealthRisks_report_full.pdfGoogle Scholar The 2017 Global Burden of Disease Study suggests there are 1.6 million deaths attributable to household air pollution annually, of which approximately one-half of a million are deaths from pneumonia in young children.8GBD 2017 Risk Factors CollaboratorsGlobal, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017.Lancet. 2018; 392: 1923-1994PubMed Google Scholar In Malawi, where at least 95% of households depend on biomass as their main source of fuel and where household air pollution levels are high, biomass smoke exposure has been thought to be responsible for a substantial burden of this disease.5Gordon S.B. Bruce N.G. Grigg J. et al.Respiratory risks form household air pollution in low and middle income countries.Lancet Respir Med. 2014; 2: 823-860Abstract Full Text Full Text PDF PubMed Scopus (469) Google Scholar,6Mortimer K. Gordon S.B. Jindal S.K. Accinelli R.A. Balmes J. Martin II, W.J. Household air pollution is a major avoidable risk factor for cardio-respiratory disease.Chest. 2012; 142: 1308-1315Abstract Full Text Full Text PDF PubMed Scopus (63) Google Scholar,9Dherani M. Pope D. Mascarenhas M. Smith K.R. Weber M. Bruce N. Indoor air pollution from unprocessed solid fuel use and pneumonia risk in children aged under five years: a systematic review and meta-analysis.Bull World Health Organ. 2008; 86: 390-398Crossref PubMed Scopus (372) Google Scholar In this context, we did a cluster-randomized controlled trial of introducing cleaner-burning biomass-fueled cookstoves to prevent pneumonia in children <5 years od in rural Malawi (the Cooking and Pneumonia Study [CAPS]).10Mortimer K. Ndamala C.B. Naunje A.W. et al.A cleaner burning biomass-fueled cookstove intervention to prevent pneumonia in children under 5 years old in rural Malawi (the Cooking and Pneumonia Study): a cluster randomised controlled trial.Lancet. 2017; 389: 167-175Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar CAPS included 10,750 children from 8626 households across 150 community-level clusters with 10,543 children from 8470 households contributing 15,991 child-years of follow-up data to the intention-to-treat analysis. Although the Integrated Management of Childhood Illness (IMCI)-defined pneumonia incidence rate overall was substantial (15.7 per 100 child-years), we found no difference in the pneumonia incidence rate between the intervention and control groups (incidence rate ratio, 1.01; 95% CI, 0.91 to 1.13; P = .80). To explore possible explanations for this finding, we now report data from CAPS on (1) the association between exposure to carbon monoxide (CO) and carboxyhemoglobin (COHb) and pneumonia, (2) a comparison of CO exposures and COHb levels in children with and without an episode of pneumonia during the trial, and (3) the effects of the intervention on personal exposure to CO and COHb levels the children who these The CAPS trial data and CO and COHb data at the of to CAPS been K. Ndamala C.B. Naunje A.W. et al.A cleaner burning biomass-fueled cookstove intervention to prevent pneumonia in children under 5 years old in rural Malawi (the Cooking and Pneumonia Study): a cluster randomised controlled trial.Lancet. 2017; 389: 167-175Abstract Full Text Full Text PDF PubMed Scopus (170) Google D. D. Grigg J. Gordon S.B. Balmes J. K. The Cooking and Pneumonia Study in a assessment of carbon monoxide exposure and carboxyhemoglobin levels in children under 5 years Health. 2018; Scopus Google Scholar CAPS was a cluster-randomized controlled trial with of that the effects of a cleaner-burning biomass-fueled cookstove intervention to the use of open on pneumonia incidence and CO exposures in children <5 years old in rural Malawi over a We 150 community-level clusters across of in the and on the Malawi The Malawi of and the of the CAPS trial Study with and and the of a for households with at least one child to years old were to for those to and was at cluster and or of to The trial was open to households with a child in the age that for during the of the trial or were recruited to 6 months the of the were to intervention and control with the use of a with from health and cluster of was to for this with the use of a in to the report form that one in children who were included in CAPS to be to in the were to the on their cluster at households cleaner-burning biomass-fueled cookstoves a and these cookstoves combustion smoke been found to be approximately with the open in were and as households open the of the trial, control households were that the intervention at the of the for and to household was every months the time the was we were months and directly the The was the incidence of pneumonia or at that were trial who were of intervention included pneumonia and pneumonia with We measured personal exposure to CO directly in children with that measured CO with an and in children aged months with the use of that measured COHb levels a that was on a D. D. Grigg J. Gordon S.B. Balmes J. K. The Cooking and Pneumonia Study in a assessment of carbon monoxide exposure and carboxyhemoglobin levels in children under 5 years Health. 2018; Scopus Google Scholar The were with the to quality the the for the COHb levels were for children the age of 6 months to to the children this age personal exposure to CO not COHb levels CO and levels were measured at and at follow-up CO were to every and in a that was around the of the child that the was to the CO were for 48 during hours when were the the of the a the to the and the data a this a to CO exposure was and COHb levels were measured when there was a between from CO were a in the at the time were the and COHb data were that been with the use of data were to a at when the to data and were on to a in for analysis. for CAPS been In we to 150 community-level clusters that approximately children to over the approximately child-years of follow-up data and to a difference in the pneumonia incidence rate between the intervention and control a rate of 5 per 100 child in children included in CAPS were for in this at were or (interquartile as (95% of pneumonia was the of pneumonia over of with was used to the CO CO with hours of measurement were the of of the were to the parts per million and the per with of the were of over hours was one or the from to the from to 48 and was hours in the was with data on and were the were to CO for were with the use of and which in a for We the and the These were as CO was to for is in and as parts per were and group (95% were were with the use of a with were used to between of of pneumonia pneumonia or pneumonia with and exposure to CO exposure and COHb an for age, of in the and and an for of was on time to of in the and CO was these as were for CO to or 6 months of age are as rate and 95% were with the use of CO as a to association with the were with COHb and CO as the and the of in the household were included as and were for time to of and for cluster at and children were to in this of with and 1805 from households data at We children intervention; control) from households between the and follow-up were from 1805 children (928 intervention; 877 control) at and from children intervention; control) with at least one follow-up who were included in the for analysis. The age of children was 25.6 months; 50.6% were at were in the intervention and control groups The follow-up was on of the = = data for children intervention; control and pneumonia at least in the a in the = = used for household in the or exposure to household as of household to or a time in the when there was not for the household to a time in the when the household did not to for children intervention; control household in a CO and COHb were at on intervention; control) and intervention; control) respectively. The of CO exposures at was to and the of COHb levels was in intervention and control groups the years of there were intervention; control) and intervention; control) of CO exposure and COHb respectively. of CO the of Carbon and to to to to to to to to to to to to to to to to to to to to to control in (95% to to to to to of to control in COHb (95% to to to to to = carbon COHb = = = parts per in a CO = carbon COHb = = = parts per were pneumonia that an incidence rate of (95% CI, to per no evidence of association between CO 1.0; 95% CI, 0.967 to 1.014; P = .53) or COHb 1.00; 95% CI, 0.993 to 1.003; P = .41) and the rate of of was with no association for pneumonia = and CO 95% CI, to 1.01; P = or COHb 1.01; 95% CI, to P = for pneumonia with = and CO 95% CI, to P = pneumonia with was associated with COHb 95% CI, 0.91 to P = where COHb levels were for no at a of was for age, of in the and follow-up time and was on an were to and 6 months of age from those 6 months of were with for CO association between and and were Median CO exposures in children with and without an episode of pneumonia during the trial were to and respectively, a difference with no of (95% CI, to P = who experienced an episode of pneumonia CO of to and those with pneumonia with low a CO of to COHb levels in children with and without an episode of pneumonia during the trial were and respectively, a difference of (95% CI, to P = with an episode of pneumonia COHb of and those with an episode that included low COHb of Median exposure to CO in the intervention and control groups was 0.34 0.15 to 0.81) and 0.37 0.15 to 0.97), respectively, a difference of (95% CI, −0.95 to 0.012; P = In for age, and the of in the the difference was (95% CI, to the intervention group CO was to and to and the intervention was COHb levels in the intervention and control groups were (95% CI, to and (95% CI, to respectively, a difference of (95% CI, to P = in for age, and the of in the the difference was (95% CI, to the intervention group COHb levels were and and the intervention was of personal exposure to household air pollution measurement of CO and and association with pneumonia in children under the age of 5 years in Malawi included children who and of CO exposure and COHb respectively, over years of Although personal exposure to CO was COHb levels were over the years of We found no association between exposure to CO over a or levels of COHb and the incidence of In there were no in the levels of CO exposure or COHb in children with or without an episode of pneumonia during the was no difference in CO and there was a difference in COHb levels between intervention and control group which is with the of intervention effect that was in the main intention-to-treat analysis. In our main trial we main explanations for the of effect of the intervention on pneumonia (1) effects of the intervention may been of air and (2) the intervention did not reduce exposures is that the between exposure to household air pollution and pneumonia in children is not as as thought and that for the of is a an intervention that to reduce exposure to household air pollution from in to on this The low CO exposure of personal CO exposure levels seen over the of the trial in trial is with of household air pollution in and in Exposure Study of and was K.R. L. et child and carbon monoxide exposures and and from a trial of cookstoves in PubMed Scopus Google be to levels of this in biomass fuel to where are when is the J. E. Smith K.R. personal exposures CO in households with PubMed Scopus Google Scholar, et exposure of and children to carbon monoxide from biomass fuels in the a measurement and 2012; PubMed Scopus Google Scholar, R. smoke in what is the between particulate carbon and 2014; PubMed Scopus Google Scholar suggests that the measurement of personal CO exposure for of time may not be a for of the effects of household air pollution exposure when is and there is no to that these personal are as The of poor with the is for the low CO exposures. In COHb levels were high and with the personal CO exposure suggest that exposure to CO as a of household air pollution is high and that COHb may a and of CO The of a of effect of the intervention on COHb CO is with this We however, that our of COHb data is in the children in pneumonia incidence is highest of of the we were that we were to measure COHb in children under the age of 6 is possible that there was a the children were the that to exposures. the is CO exposure that has been to be in the risk of pneumonia of the that we in Malawi the time as the in this and in the suggests that these exposures are not = in our of and air pollution exposure in R. M. et and air pollution exposure in Malawi a Respir Med. PubMed Scopus Google CO exposure be to be an for where is R. M. et and air pollution exposure in Malawi a Respir Med. PubMed Scopus Google N. et between household carbon monoxide and particulate matter from pollution in 142: PubMed Scopus Google Scholar In is and to measure CO and that is not for personal in young children or on the of we in this We are with the extent to which children in rural Malawi are to household air pollution that been measured this been the of in these exposures of the we and the of CO as an of household air pollution exposure in such as In settings where biomass use is common and there are of air this may not be the Although there is for a between exposure to household air pollution and pneumonia in young children and there is a of evidence for Health Organization 2014Indoor air quality guidelines: household fuel combustion.http://apps.who.int/iris/bitstream/10665/141496/1/9789241548885_eng.pdfGoogle Scholar, 5Gordon S.B. Bruce N.G. Grigg J. et al.Respiratory risks form household air pollution in low and middle income countries.Lancet Respir Med. 2014; 2: 823-860Abstract Full Text Full Text PDF PubMed Scopus (469) Google Scholar, 6Mortimer K. Gordon S.B. Jindal S.K. Accinelli R.A. Balmes J. Martin II, W.J. Household air pollution is a major avoidable risk factor for cardio-respiratory disease.Chest. 2012; 142: 1308-1315Abstract Full Text Full Text PDF PubMed Scopus (63) Google E. M. R. the effect of air pollution on pneumonia in children under 5 in low- and middle-income a systematic review of PubMed Scopus Google Household air pollution from combustion of solid fuels and Full Text Full Text PDF PubMed Scopus Google Scholar of the exposure-response to been of exposure or that been used to exposure-response on from of and air pollution S.B. Bruce N.G. Grigg J. et al.Respiratory risks form household air pollution in low and middle income countries.Lancet Respir Med. 2014; 2: 823-860Abstract Full Text Full Text PDF PubMed Scopus (469) Google E. M. R. the effect of air pollution on pneumonia in children under 5 in low- and middle-income a systematic review of PubMed Scopus Google Household air pollution from combustion of solid fuels and Full Text Full Text PDF PubMed Scopus Google Scholar is the trial of a cookstove in where an exposure-response between measured CO a for and pneumonia during the months of was K.R. Weber et of in household air pollution on pneumonia in a randomised controlled trial.Lancet. Full Text Full Text PDF PubMed Scopus Google Scholar of the of household air pollution and pneumonia, was and the infant was on the during systematic review of household air pollution exposures and pneumonia in children found were seen when were used for exposure these were not seen was an when air that included CO and particulate matter were measured E. M. R. the effect of air pollution on pneumonia in children under 5 in low- and middle-income a systematic review of PubMed Scopus Google Scholar is with the findings of our from Malawi that has found no evidence that exposure to household air pollution was associated with pneumonia in with or in children and or with the rate of on in R. M. et and air pollution exposure in Malawi a Respir Med. PubMed Scopus Google J. K. et in a of in Med. PubMed Scopus Google Scholar, S. R. Naunje et health and exposure to air pollution in children a PubMed Scopus Google Scholar, S. et air and pneumonia in a 2017; 2: PubMed Scopus Google Scholar, S. C. Naunje et and air pollution exposure in a PubMed Scopus Google Scholar The of this that is the of personal exposure to CO and COHb levels in children in rural and as of from the controlled trial of data and analysis. to follow-up and use of an pneumonia may the of the main is the of to measure personal exposure to in young children in a and that can be for of time on of Although CO are that can these CO exposure is to pneumonia and may be a poor of in settings where is We found that young children in rural Malawi experience exposure to household and of air pollution on a when data are that data from CO exposure and COHb are We found no association between exposure to CO and pneumonia incidence and no effect of the CAPS intervention on these which suggests that CO may not be an appropriate measure of household air pollution exposure in settings like rural Malawi and that there is a need to develop ways to measure particulate matter exposures directly in young children instead. is a need to the role of cleaner-burning cookstoves and fuels as health of air pollution is to be for a to control from is to air quality and the K. 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