Translational Research on Household Air Pollution Exposure and Associated Health Impacts in Low- and Middle-income Countries Öffentlichkeit
Ye, Wenlu (Fall 2021)
Published
Abstract
Nearly half of the world’s population – about 3.6 billion people – are exposed to household air pollution (HAP) from burning solid fuels such as wood, animal dung, and coal for cooking and heating. HAP has been linked to numerous adverse outcomes and is also a drag on development and environment conservation, particularly in low- and middle-income countries (LMICs). Despite the growing research on HAP in public health, knowledge gaps remain in understanding 1) the levels and composition of this environmental exposure in under-researched areas/populations; 2) the health implication, i.e., the shape of exposure-response relationships to estimate the relative risk of associated diseases/subclinical impairment; and 3) the efficacy and effectiveness of clean household energy interventions, to achieve sufficient reduction in exposures and deliver desired health benefits.
Applying a translational research framework in environmental health sciences, the research presented in this dissertation contributed to these knowledge gaps by 1) characterizing the personal exposure to HAP in rural Tibetan women and children, a population with very few direct exposure measurements; 2) assessing the cross-sectional and longitudinal exposure-response relationship between HAP exposure and blood pressure in pregnant women; and 3) examine the effect of a liquified petroleum gas (LPG) stove and fuel intervention on gestation blood pressure.
Specifically, Chapter 2 of this dissertation reflects the T1 stage of the translational research framework in environmental health sciences: observation of environmental exposure. This chapter focuses on characterizing the personal exposure to HAP (i.e., PM2.5, BC, polycyclic aromatic hydrocarbons [PAHs], and inorganic elements) from burning firewood and yak dung among women and children living in agricultural and nomadic villages of rural Tibet, China. We observed high personal HAP exposure in both women and children, particularly among those from the nomadic village where yak dung was used as a major fuel. There was also evidence of other sources, besides biomass burning, contributed to the personal PM2.5 exposure in this region. Measurement results from this analysis questioned the commonly accepted assumption that biomass burning is the single most important source of air pollution exposure in rural Tibet. Strategies to reduce HAP exposure in this region should focus on not only the stove/fuel efficiency or ventilation but also other exposure sources and behavioral factors, such as traffic and garbage burning.
Chapter 3 explores the exposure-response relationship between HAP (i.e., PM2.5, BC, and CO) exposure and blood pressure among pregnant women exclusively using biomass stoves and reflects the T2 stage of the translational research: understanding the health implication of environmental exposure. This study utilizes the baseline personal exposure and blood pressure measurements collected from 3190 pregnant women enrolled in the Household Air Pollution Intervention Network (HAPIN) randomized controlled trial (RCT) at four different countries: Guatemala, India, Peru, and Rwanda. We found that the personal exposure levels in this pregnant women cohort were consistently above the recommended WHO IT-1 for annual PM2.5 of 35 μg/m3. Blood pressure values varied by country but were generally within normotensive ranges (93%). Trial-wide, among pregnant women with exposure in the highest quartile, we observed a significant association between BC and systolic blood pressure (SBP) and an indicative positive association between PM2.5 and SBP. This study characterized personal exposure to three major household air pollutants in pregnant women using solid fuel in four diverse LMICs and illustrated the distribution and variability of blood pressure in pregnant women in their early pregnancy. The association analysis contributed to the limited evidence that HAP exposure may raise blood pressure among normotensive adults.
Analyses presented in Chapter 4 pertaining to the practice implication (T3) stage of the translational research framework. Work in this chapter assessed the efficacy of an LPG stove and fuel intervention to reduce HAP exposure and improve health. Specifically, an intention-to-treat (ITT) analysis was conducted to evaluate the intervention effects on blood pressure among pregnant HAPIN participants over their pregnancy. To explore the consistency with the ITT analysis and to further explore the association between HAP and gestational blood pressure, an exposure-response analysis was also conducted in Chapter 4 using repeated personal HAP exposure and blood pressure measurements. Results from this analysis showed that the LPG stove and fuel intervention led to a large reduction in the post-randomization personal exposures to PM2.5, BC, and CO. However, the intervention showed no protective effect on gestational blood pressure in our low antenatal risk profile pregnant women cohort. Nevertheless, this study added to the limited evidence of the association between HAP exposure and blood pressure in pregnant women with repeated measurements in four LMICs and demonstrated the effect of the LPG stove and fuel intervention on reducing personal exposures to PM2.5, BC, and CO.
Table of Contents
List of Figures
List of Tables
Chapter 1
Introduction
1.1 Background
1.2 Context—Translational research
1.3 Review of Literature
1.3.1 Household air pollution exposure in Tibet
1.3.2 Household air pollution and blood pressure among pregnant women
1.3.3 Interventions to reduce household air pollution exposure and improve health
Chapter 2
Household Air Pollution and Personal Exposure from Burning Firewood and Yak Dung in Summer in the Eastern Tibetan Plateau
2.1 Background
2.2 Methods
2.2.1 Study location
2.2.2 Field survey
2.2.3 Exposure and indoor concentration sampling instruments and sampling strategy
2.2.4 Exposure and indoor concentration data processing and chemical speciation analysis
2.2.5 Statistical analysis
2.3 Results
2.3.1 Survey results
2.3.2 Air quality measurement results
2.3.3 Statistical analysis results
2.4 Discussion
2.5 Conclusion
Chapter 3
Baseline associations between household air pollution and maternal blood pressure in the Household Air Pollution Intervention Network (HAPIN) multi-country randomized controlled trial
3.1 Background
3.2 Methods
3.2.1 Study design, location, and population
3.2.2 Measurement of personal exposure to household air pollution
3.2.3 Measurement of blood pressure
3.2.4 Questionnaires and other measurements
3.2.5 Statistical analysis
3.3 Results
3.3.1 Participant characteristics
3.3.3 Personal exposures to PM2.5, BC, and CO
3.3.4 Associations between household air pollution and gestational blood pressure
3.4 Discussion
Chapter 4
Effects of a cleaner energy intervention on gestational blood pressure: findings from the Household Air Pollution Intervention Network (HAPIN) randomized controlled trial
4.1 Background
4.2 Methods
4.2.1 Study Site and Population
4.2.2 Measurement of blood pressure
4.2.3 Measurement of household air pollution exposure
4.2.4 Statistical analysis
4.3 Results
4.3.1 Participant characteristics
4.3.2 Effects of the intervention on household air pollution exposures
4.3.3 Blood pressure measurements
4.3.4 Intention-to-Treat analysis
4.3.4 Exposure-Response analysis
4.4 Discussion
Chapter 5
Discussion
5.1 Key contributions
5.2 Reflection and future work
5.3 Investigator Role and Responsibility
APPENDICES
Appendix A Supplementary Information for Chapter 2
Appendix B Supplementary Information for Chapter 3
Appendix C Supplementary Information for Chapter 4
References
About this Dissertation
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