Personal exposure to air pollution and early child development: Analyses from the Household Air Pollution Intervention Network Restricted; Files Only
de León, Oscar (Summer 2024)
Abstract
Early Child Development (ECD) is a complex process that encompasses physical, cognitive, social, and emotional changes from birth to early childhood. ECD is preceded by gestational processes that affect fetal growth and fetal brain development. Fetal development and ECD are influenced by a combination of both intrinsic and environmental factors, including genetics, maternal health, nutrition, exposure to environmental pollutants, and child care, among many others. Exposure to air pollution is one factor that has been associated with delays in development, with effects on all domains of ECD and at different timepoints related to varying sources of pollution. Personal exposure to air pollution (PAP) can be estimated through a variety of methods, from environmental models to direct measurement in the air a person is breathing, but assessments closer to direct measurement are more accurate. Directly measuring PAP is labor and resource intensive, so in studies with constrained resources compromises between accuracy and cost are necessary. The physical components of ECD in the form of linear growth and weight gain are typically assessed directly by trained evaluators performing the relevant measurements. These physical assessments allow us to identify growth patterns and compare them to reference populations, and determine if children are suffering growth faltering in the form of stunting or wasting. The behavioral components of ECD can be assessed directly in very young children by observation from trained evaluators, or indirectly by caretaker reports of the behavior they observe. These assessments typically result in scores for ECD domains reflecting a variety of cognitive, social, and emotional characteristics, and provide a way of establishing individual development as compared to a reference or differences between child populations. The goal of this dissertation is to evaluate possible associations between exposure to fine particulate matter (PM2.5) and delays in early child development in the Household Air Pollution Intervention Network (HAPIN) trial.
In Aim 1 we evaluated the association between average personal exposures to PM2.5 during the gestational and post-natal period and stunting, wasting, and underweight at 12 months of age. We found that an interquartile increase in gestational exposure to PM2.5 (74.9 ug/m3) was associated with 8% (95% CI: 1 - 15%) increase in the risk of stunting.
In Aim 2 we evaluated the effect of the HAPIN trial intervention on the cognitive, motor, language, and socio-emotional development scores at 12 months of age. We found that the intervention did not have an effect on the child development scores under intention-to-treat, but resulted in higher ECD scores for participants who received the intervention before 18 weeks of gestation compared to those receiving the intervention later (adjusted mean difference 0.1, 95% CI: 0.032 to 0.169).
In Aim 3 we evaluated the association between average personal exposures to PM2.5 during the gestational and post-natal period and cognitive, motor, language, and socio-emotional development scores at 12 months of age. We did not find consistent associations between the gestational or post-natal exposure to PM2.5 and ECD scores at 12 months
Table of Contents
1 Introduction
Motivation 1
Delays in linear growth and weight gain 2
Delays in developmental milestones 4
Causes of delays in ECD 6
Effects of exposure to air pollution on ECD 7
The HAPIN trial 7
Dissertation aims 8
2 Aim 1: Exposure–response relationships between personal exposure to fine particulate matter (PM2.5) and growth faltering at 12 months: an analysis of the multi-country Household Air Pollution Intervention Network (HAPIN) trial 10
Abstract 11
Introduction 12
Methods 13
Study design and participants 13
Personal exposure to air pollutants 14
Anthropometric outcomes and assessment 15
Covariates 15
Statistical analysis 18
Ethics review and trial registration statement 19
Results 20
Study design and participants 20
Missingness and quality control 26
Exposure to PM2.5 30
Anthropometric assessment and outcomes 31
Associations between exposure to air pollution and growth faltering 33
Discussion 42
Supplemental information 46
Appliances and assets considered for the socioeconomic status evaluation of participating households 46
Exposure and outcome assessments performed and missed over time per country 46
Distribution of anthropometric z-scores given availability of exposure data 48
Additional information about associations between exposure to PM2.5 and Early Child Development 50
Additional subgroup analyses for the association with exposure to PM2.5 55
Influence of the baseline exposure on the gestational period exposure average 57
3 Aim 2: Effects of a cleaner fuel intervention on child development at 12 months: an analysis of the multi-country Household Air Pollution Intervention Network (HAPIN) trial 58
Abstract 59
Introduction 60
Methods 61
Study design and participants 61
Early child development assessment and outcomes 62
Covariates 63
Statistical analysis 64
Ethics review and trial registration statement 64
Results 65
Study design and participants 65
Effect of the HAPIN LPG intervention on ECD 72
Discussion 74
4 Aim 3: Exposure–response relationships between personal exposure to fine particulate matter (PM2.5) and early child development at 12 months: an analysis of the multi-country Household Air Pollution Intervention Network (HAPIN) trial 76
Abstract 77
Introduction 78
Methods 80
Study design and participants 80
Personal exposure to air pollutants 80
Early child development assessment and outcomes 81
Covariates 83
Statistical analysis 84
Ethics review and trial registration statement 85
Results 86
Study design and participants 86
Missingness and Quality Control 92
Exposure to PM2.5 96
Early Child Development assessment and outcomes 97
Associations between exposure to air pollution and Early Child Development 99
Discussion 105
Supplemental information 109
Appliances and assets considered for the socioeconomic status evaluation of participating households 109
Exposure and outcome assessments performed and missed over time per country 109
Distribution of CREDI scores given availability of exposure data 111
Distribution of age-standardized scores for each ECD domain 114
Additional information about associations between exposure to PM2.5 and Early Child Development 115
Influence of the baseline exposure on the gestational period exposure average 122
5 Discussion 123
Summary of contributions 124
Reflections 126
Directions for future research 128
Appendix 130
A HAPIN Investigators 130
B Growth faltering analysis plan 132
C Developmental milestones analysis plan 146
D CREDI data cleaning 154
E Socioeconomic status score 167
F Analysis environment information 170
Bibliography 172
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