Heterogeneity in Pulmonary Response to a Prescribed Commute Open Access

Yngve, Leah (2014)

Permanent URL: https://etd.library.emory.edu/concern/etds/hq37vp10x?locale=en
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Abstract

Introduction: Many people are subjected to daily exposures of vehicle-related air pollution while commuting to work or otherwise. While studies have demonstrated that pulmonary inflammation is associated with exposure to vehicle-related air pollution, variations in response due to demographic characteristics, geographic characteristics, lifestyle factors, and ambient pollution have scarcely been studied previously.

Methods: 42 study participants were recruited to participate in two 2-hour scripted commutes in Atlanta, GA between the hours of 7am and 9am. Sub-clinical health measurements assessing pulmonary inflammation, lung function, and cardiovascular function were recorded immediately before the commute, directly after the commute, and every hour for 3 hours following the commute. The estimated change in exhaled nitric oxide (eNO), an indicator of pulmonary inflammation, following the commute was assessed individually and by various demographic, geographic, lifestyle, and ambient pollution factors to examine heterogeneity in pulmonary response to a commute.

Results: Exhaled nitric oxide was significantly elevated from the baseline measurement for all measurements taken following the commute. The response was not significantly different between any of the variables examined except for the distance participants traveled to the study site. At the last time point taken 4 hours after the commute, the change in eNO was significantly different (p=0.0229) with a greater response in participants that traveled less than participants that traveled more prior to the study commute.

Conclusions: Across differences in physical and environmental characteristics, study participants displayed sub-clinical increases in pulmonary inflammation following a commute exposure. These results demonstrate one effect of vehicle-related air pollution that a large portion of the population is exposed to and suggest factors that may influence a difference in response.

Table of Contents

INTRODUCTION: 1
METHODS: 4
STUDY DESIGN 4
HEALTH MEASUREMENTS AND PARTICIPANT CHARACTERISTICS 4
PHYSICAL ACTIVITY 6
EXPOSURE MEASUREMENTS 6
STATISTICAL ANALYSIS 8
RESULTS: 10
STRATIFIED AND INTERACTION RESULTS 10
Age 11
Sex 11
Weight Status 11
Race 12
Physical Activity 12
Highway/Major Road Exposure 12
Commute Mode 13
Distance to Study Site 13
Average Daily Minutes Spent Commuting 13
Previous 24 Hours Average Ambient PM2.5 14
Previous 24 Hours Average Ambient O3 14
Concurrent 2-Hour Average Ambient PM2.5 14
Concurrent 2-Hour Average Ambient O3 15
DISCUSSION: 15
STRATIFIED MODELS 16
Physical Characteristics 16
Lifestyle Characteristics 16
Ambient Pollution 19
KEY FINDINGS 20
STRENGTHS 23
LIMITATIONS 23
IMPLICATIONS 24
CONCLUSIONS 25
REFERENCES 26
TABLE 1. BASELINE CHARACTERISTICS OF STUDY PARTICIPANTS: 29
TABLE 2. EFFECT ESTIMATES FOR THE CHANGE IN EXHALED NITRIC OXIDE (ENO) FROM BASELINE UNSTRATIFIED AND STRATIFIED BY INCREASING DISTANCE TO STUDY SITE: 30
TABLE 3. RESULTS OF P-VALUES FROM INTERACTION MODELS OF INDIVIDUAL CHARACTERISTICS WITH COMMUTE NUMBER AND POST-COMMUTE TIME POINTS: 31
FIGURE 1. PERCENT CHANGE IN EXHALED NITRIC OXIDE FROM BASELINE LEVELS FOR ALL COMMUTES: 32
FIGURE 2. PERCENT CHANGE IN EXHALED NITRIC OXIDE FROM BASELINE BY DISTANCE TO STUDY SITE TERTILES: 32
FIGURE 3. PERCENT CHANGE IN ENO: DIFFERENCE BETWEEN THE PERCENT CHANGE IN ENO FROM THE UNSTRATIFIED MODEL AND THE CORRESPONDING PERCENT CHANGE IN THE STRATIFIED MODELS
A. IMMEDIATELY POST-COMMUTE: 33
B. 1-HOUR AFTER THE COMMUTE: 34
C. 2-HOURS AFTER THE COMMUTE: 35
D. 3-HOURS AFTER THE COMMUTE: 36

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