Preliminary Assessment of Personal Time Activity Patterns and Change of Traffic Pollutant Exposure: A multi-month cohort and panel based study Public

Abstract

Introduction: The evaluation of time-activity patterns is important in estimating personal exposure to air pollution, especially since the pollution levels may vary by location and the person has different temporal and locational patterns. Past studies have used traditional surrogate methods that were focused on data collected from centralized monitoring locations, which did not accurately characterize the pollutant variability we see nowadays. Recent studies have shown a trend in measuring personal exposure at the individual level by focusing on the microenvironment of each subject. Our study evaluated the usage of such methods in a small cohort and validated the association between personal exposure and background concentrations.

Methods: Data was collected from 51 subjects at the Georgia Institute of Technology campus. We collected particulate matter (PM2.5), nitrogen oxide (NOx), and black carbon (BC) concentrations over a 48-hr data collection cycle. At the same time weekly geospatial and activity data was collected using geospatial trackers. The statistical analysis was conducted to evaluate and validate the association between personal exposure and time-activity patterns.

Results: The data showed the subjects spent a majority of their time within an indoor microenvironment and showed bimodal patterns in terms of distance from the pollutant source. Concentrations also were different by week during the data collection period and seemed to be associated with background levels, but not at a statistically significant level. We also found that there were significant associations between personal pollutant exposure and indoor microenvironments, background pollutant concentrations measured at centralized location, and for PM2.5 the distance from the Connector.

Discussion: Our study did have certain limitations that became evident during the analysis due to mechanical and instrumental errors that occurred during the data collection process. The similarity in the subjects' time-activity patterns and microenvironment emphasized the importance of personal monitoring compared to the traditional methods. As a part of a multi-tiered study we hope to further investigate the relation personal exposure data has with other factors that are related to exposure and health, such as metabolomics data.

Table of Contents

Introduction.............................................................................................1

Methods...................................................................................................4

Participant Recruitment............................................................................5

Outdoor and Roadside Monitoring.............................................................7

Personal Exposure....................................................................................8

Data and Statistical Analysis.....................................................................10

Results....................................................................................................11

GPS Results.............................................................................................12

PM2.5, NO2, and BC Measurements...........................................................15

Discussion...............................................................................................24

Limitations.............................................................................................28

Conclusion..............................................................................................29

References..............................................................................................31

About this Master's Thesis

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School	Rollins School of Public Health
Department	Environmental Health
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Environmental Health
Mot-clé	Nitrogen oxides Particulate matter Traffic pollutants Air pollution Personal exposure Black carbon Global positioning system
Committee Chair / Thesis Advisor	Sarnat, Jeremy, Emory University
Committee Members	Tolbert, Paige, Emory University
Partnering Agencies	University, college or educational institution (other than Emory)

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