Household Air Pollution
2021; Elsevier BV; Volume: 160; Issue: 5 Linguagem: Inglês
10.1016/j.chest.2021.08.049
ISSN1931-3543
Autores Tópico(s)Climate Change and Health Impacts
ResumoFOR RELATED ARTICLE, SEE PAGE 1634The great majority of the world’s population breathe air that is polluted with average levels of particulate matter <2.5 μm in diameter (PM2.5) that exceeds the World Health Organization Air Quality Guideline.1Health Effects InstituteState of Global Air 2020. Special Report. Health Effects Institute, 2020Google Scholar In low-income and middle-income countries household air pollution (HAP) (air pollution in the home that arises primarily from the use of dirty-burning fuels for lighting, heating, and cooking) is a major component of overall air pollution exposure.1Health Effects InstituteState of Global Air 2020. Special Report. Health Effects Institute, 2020Google Scholar Although estimates have varied somewhat over time, it is thought that approximately 2 million people die every year of diseases attributable to HAP.1Health Effects InstituteState of Global Air 2020. Special Report. Health Effects Institute, 2020Google Scholar,2Lee K.K. Bing R. Kiang J. et al.Adverse health effects associated with household air pollution: a systematic review, meta-analysis, and burden estimation study.Lancet Glob Health. 2020; 8: e1427-e1434Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar Of these, pneumonia in children <5 years old is of particular concern because these deaths represent so much loss of life and, where attributed to HAP, are arguably completely preventable.Although it seems clear that the path to preventing these deaths caused by HAP lies with cleaning up the air in homes, what we do not know is how to do this in a way that is acceptable to households and communities, affordable, and clinically and cost-effective. Perhaps surprisingly for an exposure that is widely considered to cause so much morbidity and death, there have been few trials of HAP reduction interventions on clinical outcomes.3Mortimer K Balmes JB Cookstove trials and tribulations: what is needed to decrease the burden of household air pollution?.Ann Am Thor Soc. 2018; 15: 539-541Crossref PubMed Scopus (21) Google Scholar,4Saleh S. Shepherd W. Jewell C. et al.Air pollution interventions and respiratory health: a systematic review.Int J Tuberc Lung Dis. 2020; 24: 150-164Crossref PubMed Scopus (16) Google Scholar Those that have been done and reported to date have focused on reducing HAP related to cooking.3Mortimer K Balmes JB Cookstove trials and tribulations: what is needed to decrease the burden of household air pollution?.Ann Am Thor Soc. 2018; 15: 539-541Crossref PubMed Scopus (21) Google Scholar,4Saleh S. Shepherd W. Jewell C. et al.Air pollution interventions and respiratory health: a systematic review.Int J Tuberc Lung Dis. 2020; 24: 150-164Crossref PubMed Scopus (16) Google Scholar The first of these to report was by Romieu et al5Romieu I. Riojas-Rodríguez H. Marrón-Mares A.T. 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: 649-656Crossref PubMed Scopus (209) Google Scholar who studied the effects of chimney stove intervention on cough and decline in FEV1 in 552 women in rural Mexico over 10 months. This was followed by the Randomized Exposures Study of Pollution Indoors and Respiratory Effects (RESPIRE) study that was also a trial of a chimney stove intervention, this time focused on physician-diagnosed pneumonia in 518 young children.6Smith K.R. McCracken J.P. Weber M.W. et al.Effect of reduction in household air pollution on childhood pneumonia in Guatemala (RESPIRE): a randomised controlled trial.Lancet. 2011; 378: 1717-1726Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar Neither study found a statistically significant effect on the primary outcome, although there were signals of potential benefit in secondary and per-protocol analyses that included physician-diagnosed severe pneumonia in RESPIRE. The Cooking and Pneumonia Study in Malawi tested an intervention comprising two cleaner-burning biomass-fueled cookstoves with a solar charger on pneumonia in 10,750 children <5 years old.7Mortimer 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 (189) Google Scholar Again, there was no signal of beneficial effect of the intervention on the primary outcome.In response to the mounting evidence that biomass-burning cookstoves were not delivering the hoped-for health benefits, subsequent trials moved on to explore cleaner cooking fuels but retained a focus just on addressing cooking-related sources of HAP. Alexander et al8Alexander D. Northcross A. Wilson N. et al.Randomized controlled ethanol cookstove intervention and blood pressure in pregnant Nigerian women.Am J Respir Crit Care Med. 2017; 195: 1629-1639Crossref PubMed Scopus (59) Google Scholar evaluated the effects of an ethanol-fueled stove on BP in 324 pregnant women in Ibadan, Nigeria, and found no significant effect of the intervention on systolic BP but did see an effect on diastolic BP. Most recently, Checkley et al9Checkley W. Williams K.N. Kephart J.L. et al.Effects of a household air pollution intervention with liquefied petroleum gas on cardiopulmonary outcomes in Peru: a randomized controlled trial.Am J Respir Crit Care Med. 2021; 203: 1386-1397Crossref PubMed Scopus (16) Google Scholar reported on the Cardiopulmonary Outcomes and Household Air Pollution trial that assessed the effects of a 1-year liquefied petroleum gas intervention on BP, peak expiratory flow, and respiratory symptoms in 180 women 25 to 64 years old in rural Peru. No beneficial effects of the intervention were seen on any of these outcomes.The Ghana Randomized Air Pollution and Health Study (GRAPHS) straddled both the biomass and liquefied petroleum gas worlds by studying the effects of two interventions (a cleaner-burning biomass-fueled cookstove or liquefied petroleum gas) on pneumonia in children <1 year old who had been diagnosed by World Health Organization Integrated Management of Childhood Illness criteria.10Jack D.W. Asante K.P. Wylie B.J. et al.Ghana randomized air pollution and health study (GRAPHS): study protocol for a randomized controlled trial.Trials. 2015; 16: 420Crossref PubMed Scopus (51) Google Scholar Although the full trial results are awaited, important data from GRAPHS relating to pre- and post-natal HAP exposure and pneumonia in the first year of life are presented in this issue of CHEST.11Kinney P.L. Asante K.-P. Lee A.G. et al.Prenatal and postnatal household air pollution exposures and pneumonia risk: evidence from the Ghana randomized air pollution and health study..Chest. 2021; 160: 1634-1644Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar One thousand four hundred fourteen nonsmoking pregnant women at less than 24 weeks gestation were recruited; four prenatal and three postnatal measurements of carbon monoxide were used as an indicator of HAP. Data from 1,141 infants who represented 55,605 child-weeks of follow-up were included in the analysis. The risk of pneumonia and severe pneumonia was found to increase by 10% and 15% per 1 ppm increase in prenatal carbon monoxide (CO) exposures and by 6% per 1 ppm increase in postnatal CO exposures; female infants appeared to be particularly susceptible.These findings from GRAPHS focus attention on the prenatal period as a time in life when HAP exposure reduction interventions may have the greatest potential to deliver health benefits. This is an important step forward because the trials that have reported data the study of pneumonia in young children have focused on the postnatal period. Exposure-response analyses from RESPIRE found that a 1.1 ppm reduction in infant CO exposure was associated with an 18% reduction in physician-diagnosed pneumonia.6Smith K.R. McCracken J.P. Weber M.W. et al.Effect of reduction in household air pollution on childhood pneumonia in Guatemala (RESPIRE): a randomised controlled trial.Lancet. 2011; 378: 1717-1726Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar although no association was seen between CO exposure and pneumonia in the Cooking and Pneumonia Study.12Mortimer K Lesosky M Semple S et al.Pneumonia and exposure to household air pollution in children under the age of 5 years in rural Malawi: findings from the cooking and pneumonia study.Chest. 2020; 158: 501-511Abstract Full Text Full Text PDF PubMed Scopus (13) Google ScholarThe exposure-response relationship between CO and pneumonia was seen in GRAPHS, despite low average levels of exposure to CO (1.3 ppm prenatal period; 0.9 ppm postnatal period). This contrasts with PM2.5 exposure measurements that were high (average pre- and postnatal 85.1 μg/m3 and 68.3 μg/m3, respectively) but did not show an exposure-response with pneumonia. These discrepancies are difficult to explain, although PM2.5 was only measured in a subset of GRAPHS participants. Other studies have found limited correlation between exposure to these two pollutants, despite the pollutants largely being derived from the same sources; these different pollutants may well have different mechanisms by which they cause adverse effects.13Nightingale R Lesosky M Flitz G et al.Non-communicable respiratory disease and air pollution exposure in Malawi (CAPS): a cross-sectional study.Am J Respir Crit Care Med. 2019; 199: 613-621Crossref PubMed Scopus (29) Google ScholarAnother consideration here is the possibility of confounding by other poverty-related factors. It is possible that the association observed in some studies between HAP and pneumonia is explained, at least partly, in this way. If true, then this would also go some way to explaining the reason that trials of interventions focused on cookstoves and that HAP exposure reduction date has not delivered the much hoped-for health benefits. It is a daunting prospect, but the signs are all pointing at future trials in this field that must evaluate interventions that go well beyond tackling cooking-associated HAP. Addressing all sources of air pollution in the home (and elsewhere) with a focus on clean air is likely to be needed to achieve a reduction in HAP-related morbidity and death across the life course.1Health Effects InstituteState of Global Air 2020. Special Report. Health Effects Institute, 2020Google Scholar,2Lee K.K. Bing R. Kiang J. et al.Adverse health effects associated with household air pollution: a systematic review, meta-analysis, and burden estimation study.Lancet Glob Health. 2020; 8: e1427-e1434Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar Even then it may not be sufficient to address air quality poverty in isolation of the wider context of poverty in which HAP sits. Whatever the next steps might be, these data from GRAPHS remind us of the importance of protecting human life from the scourges of air quality poverty from the very earliest of opportunities. FOR RELATED ARTICLE, SEE PAGE 1634The great majority of the world’s population breathe air that is polluted with average levels of particulate matter <2.5 μm in diameter (PM2.5) that exceeds the World Health Organization Air Quality Guideline.1Health Effects InstituteState of Global Air 2020. Special Report. Health Effects Institute, 2020Google Scholar In low-income and middle-income countries household air pollution (HAP) (air pollution in the home that arises primarily from the use of dirty-burning fuels for lighting, heating, and cooking) is a major component of overall air pollution exposure.1Health Effects InstituteState of Global Air 2020. Special Report. Health Effects Institute, 2020Google Scholar Although estimates have varied somewhat over time, it is thought that approximately 2 million people die every year of diseases attributable to HAP.1Health Effects InstituteState of Global Air 2020. Special Report. Health Effects Institute, 2020Google Scholar,2Lee K.K. Bing R. Kiang J. et al.Adverse health effects associated with household air pollution: a systematic review, meta-analysis, and burden estimation study.Lancet Glob Health. 2020; 8: e1427-e1434Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar Of these, pneumonia in children <5 years old is of particular concern because these deaths represent so much loss of life and, where attributed to HAP, are arguably completely preventable. FOR RELATED ARTICLE, SEE PAGE 1634 FOR RELATED ARTICLE, SEE PAGE 1634 Although it seems clear that the path to preventing these deaths caused by HAP lies with cleaning up the air in homes, what we do not know is how to do this in a way that is acceptable to households and communities, affordable, and clinically and cost-effective. Perhaps surprisingly for an exposure that is widely considered to cause so much morbidity and death, there have been few trials of HAP reduction interventions on clinical outcomes.3Mortimer K Balmes JB Cookstove trials and tribulations: what is needed to decrease the burden of household air pollution?.Ann Am Thor Soc. 2018; 15: 539-541Crossref PubMed Scopus (21) Google Scholar,4Saleh S. Shepherd W. Jewell C. et al.Air pollution interventions and respiratory health: a systematic review.Int J Tuberc Lung Dis. 2020; 24: 150-164Crossref PubMed Scopus (16) Google Scholar Those that have been done and reported to date have focused on reducing HAP related to cooking.3Mortimer K Balmes JB Cookstove trials and tribulations: what is needed to decrease the burden of household air pollution?.Ann Am Thor Soc. 2018; 15: 539-541Crossref PubMed Scopus (21) Google Scholar,4Saleh S. Shepherd W. Jewell C. et al.Air pollution interventions and respiratory health: a systematic review.Int J Tuberc Lung Dis. 2020; 24: 150-164Crossref PubMed Scopus (16) Google Scholar The first of these to report was by Romieu et al5Romieu I. Riojas-Rodríguez H. Marrón-Mares A.T. 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: 649-656Crossref PubMed Scopus (209) Google Scholar who studied the effects of chimney stove intervention on cough and decline in FEV1 in 552 women in rural Mexico over 10 months. This was followed by the Randomized Exposures Study of Pollution Indoors and Respiratory Effects (RESPIRE) study that was also a trial of a chimney stove intervention, this time focused on physician-diagnosed pneumonia in 518 young children.6Smith K.R. McCracken J.P. Weber M.W. et al.Effect of reduction in household air pollution on childhood pneumonia in Guatemala (RESPIRE): a randomised controlled trial.Lancet. 2011; 378: 1717-1726Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar Neither study found a statistically significant effect on the primary outcome, although there were signals of potential benefit in secondary and per-protocol analyses that included physician-diagnosed severe pneumonia in RESPIRE. The Cooking and Pneumonia Study in Malawi tested an intervention comprising two cleaner-burning biomass-fueled cookstoves with a solar charger on pneumonia in 10,750 children <5 years old.7Mortimer 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 (189) Google Scholar Again, there was no signal of beneficial effect of the intervention on the primary outcome. In response to the mounting evidence that biomass-burning cookstoves were not delivering the hoped-for health benefits, subsequent trials moved on to explore cleaner cooking fuels but retained a focus just on addressing cooking-related sources of HAP. Alexander et al8Alexander D. Northcross A. Wilson N. et al.Randomized controlled ethanol cookstove intervention and blood pressure in pregnant Nigerian women.Am J Respir Crit Care Med. 2017; 195: 1629-1639Crossref PubMed Scopus (59) Google Scholar evaluated the effects of an ethanol-fueled stove on BP in 324 pregnant women in Ibadan, Nigeria, and found no significant effect of the intervention on systolic BP but did see an effect on diastolic BP. Most recently, Checkley et al9Checkley W. Williams K.N. Kephart J.L. et al.Effects of a household air pollution intervention with liquefied petroleum gas on cardiopulmonary outcomes in Peru: a randomized controlled trial.Am J Respir Crit Care Med. 2021; 203: 1386-1397Crossref PubMed Scopus (16) Google Scholar reported on the Cardiopulmonary Outcomes and Household Air Pollution trial that assessed the effects of a 1-year liquefied petroleum gas intervention on BP, peak expiratory flow, and respiratory symptoms in 180 women 25 to 64 years old in rural Peru. No beneficial effects of the intervention were seen on any of these outcomes. The Ghana Randomized Air Pollution and Health Study (GRAPHS) straddled both the biomass and liquefied petroleum gas worlds by studying the effects of two interventions (a cleaner-burning biomass-fueled cookstove or liquefied petroleum gas) on pneumonia in children <1 year old who had been diagnosed by World Health Organization Integrated Management of Childhood Illness criteria.10Jack D.W. Asante K.P. Wylie B.J. et al.Ghana randomized air pollution and health study (GRAPHS): study protocol for a randomized controlled trial.Trials. 2015; 16: 420Crossref PubMed Scopus (51) Google Scholar Although the full trial results are awaited, important data from GRAPHS relating to pre- and post-natal HAP exposure and pneumonia in the first year of life are presented in this issue of CHEST.11Kinney P.L. Asante K.-P. Lee A.G. et al.Prenatal and postnatal household air pollution exposures and pneumonia risk: evidence from the Ghana randomized air pollution and health study..Chest. 2021; 160: 1634-1644Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar One thousand four hundred fourteen nonsmoking pregnant women at less than 24 weeks gestation were recruited; four prenatal and three postnatal measurements of carbon monoxide were used as an indicator of HAP. Data from 1,141 infants who represented 55,605 child-weeks of follow-up were included in the analysis. The risk of pneumonia and severe pneumonia was found to increase by 10% and 15% per 1 ppm increase in prenatal carbon monoxide (CO) exposures and by 6% per 1 ppm increase in postnatal CO exposures; female infants appeared to be particularly susceptible. These findings from GRAPHS focus attention on the prenatal period as a time in life when HAP exposure reduction interventions may have the greatest potential to deliver health benefits. This is an important step forward because the trials that have reported data the study of pneumonia in young children have focused on the postnatal period. Exposure-response analyses from RESPIRE found that a 1.1 ppm reduction in infant CO exposure was associated with an 18% reduction in physician-diagnosed pneumonia.6Smith K.R. McCracken J.P. Weber M.W. et al.Effect of reduction in household air pollution on childhood pneumonia in Guatemala (RESPIRE): a randomised controlled trial.Lancet. 2011; 378: 1717-1726Abstract Full Text Full Text PDF PubMed Scopus (386) Google Scholar although no association was seen between CO exposure and pneumonia in the Cooking and Pneumonia Study.12Mortimer K Lesosky M Semple S et al.Pneumonia and exposure to household air pollution in children under the age of 5 years in rural Malawi: findings from the cooking and pneumonia study.Chest. 2020; 158: 501-511Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar The exposure-response relationship between CO and pneumonia was seen in GRAPHS, despite low average levels of exposure to CO (1.3 ppm prenatal period; 0.9 ppm postnatal period). This contrasts with PM2.5 exposure measurements that were high (average pre- and postnatal 85.1 μg/m3 and 68.3 μg/m3, respectively) but did not show an exposure-response with pneumonia. These discrepancies are difficult to explain, although PM2.5 was only measured in a subset of GRAPHS participants. Other studies have found limited correlation between exposure to these two pollutants, despite the pollutants largely being derived from the same sources; these different pollutants may well have different mechanisms by which they cause adverse effects.13Nightingale R Lesosky M Flitz G et al.Non-communicable respiratory disease and air pollution exposure in Malawi (CAPS): a cross-sectional study.Am J Respir Crit Care Med. 2019; 199: 613-621Crossref PubMed Scopus (29) Google Scholar Another consideration here is the possibility of confounding by other poverty-related factors. It is possible that the association observed in some studies between HAP and pneumonia is explained, at least partly, in this way. If true, then this would also go some way to explaining the reason that trials of interventions focused on cookstoves and that HAP exposure reduction date has not delivered the much hoped-for health benefits. It is a daunting prospect, but the signs are all pointing at future trials in this field that must evaluate interventions that go well beyond tackling cooking-associated HAP. Addressing all sources of air pollution in the home (and elsewhere) with a focus on clean air is likely to be needed to achieve a reduction in HAP-related morbidity and death across the life course.1Health Effects InstituteState of Global Air 2020. Special Report. Health Effects Institute, 2020Google Scholar,2Lee K.K. Bing R. Kiang J. et al.Adverse health effects associated with household air pollution: a systematic review, meta-analysis, and burden estimation study.Lancet Glob Health. 2020; 8: e1427-e1434Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar Even then it may not be sufficient to address air quality poverty in isolation of the wider context of poverty in which HAP sits. Whatever the next steps might be, these data from GRAPHS remind us of the importance of protecting human life from the scourges of air quality poverty from the very earliest of opportunities. Prenatal and Postnatal Household Air Pollution Exposures and Pneumonia Risk: Evidence From the Ghana Randomized Air Pollution and Health StudyCHESTVol. 160Issue 5PreviewPrenatal household air pollution exposure increased risk of pneumonia and severe pneumonia in the first year of life. Clean-burning interventions may be most effective when begun prenatally. Full-Text PDF
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