Outdoor Air Pollution and Children´s Asthma in the Census Metropolitan Area of Edmonton, Alberta: the Influence of Place of Residence and Socioeconomic Position

  • Author / Creator
    Rodriguez Villamizar, Laura A
  • Background: Asthma is the most common chronic respiratory disease in children and air pollution has been implicated in its development and exacerbations worldwide. The Census Metropolitan Area of Edmonton (CMAE), Alberta, has unique air pollution sources (traffic and industrial related air pollution) compared to other Canadian cities. Previous studies conducted in the Edmonton area between 1992 and 2002 indicated that ED visits for asthma were associated with day-to-day increases in almost all the main air pollutants and that these associations were stronger among children, and older adults. Since that time, sources of air pollution and asthma management have changed. The short-term effect of multiple air pollutants on ED visits for asthma, its variation at intra-urban scale, and the effect of traffic and industrial pollution sources remain unclear in the CMAE. Similarly, the capacity of the socioeconomic position (SEP) to modify these relationships has not been explored. Objectives: To determine how place of residence and SEP influence the association between short-term variations in outdoor air pollution and ED visits for children with acute asthma in the CMAE, between April 1, 2004 and March 31, 2010 by: (1) conducting a literature review of the effect-modifier role of the SEP on the relationship between outdoor air pollution and ED visits for asthma in children; (2) analysing the relationship between the exposure to multiple air pollutants and ED visits for asthma and the effect measure modification by the SEP at individual level; (3) analysing the relationship between traffic-related air pollution, SEP and ED visits for asthma at small-area level; and (4) exploring the relationship between proximity to industrial sources of air pollution and ED visits for asthma in children. Methods: For objective 1, a systematic review of the literature was conducted. For objective 2, a case-crossover study was conducted using the Air Quality Health Index (AQHI) as a composite air quality measure, and NO2, O3, and PM2.5 as single pollutants. For objective 3, a small-area case-crossover study was conducted at the dissemination area level using estimations of NO2 concentration, a proxy of traffic air pollution exposure, applying a city-specific land use regression model. For objective 4, a spatial cluster analysis of disease was conducted around the two main industrial areas in the CMAE. Records of ED visits for asthma were obtained from hospital ED facilities in the Edmonton area and daily air pollution data were obtained from Environment Alberta. Health premium subsidy status was used as an individual proxy for SEP and the Chan’s Canadian socioeconomic index as an area-level SEP variable. Results: The ED visits for asthma in children, the AQHI values and the air concentrations of NO2, PM2.5 all decreased during the study period compared to the previous decade. Day-to-day increase in the city-wide AQHI values or in the traffic-related air pollution at dissemination area level did not increase hospital ED visits for asthma. The SEP, measured at individual or small-area level, did not modify the effect of air pollution on ED visits for asthma, in concordance with the results of the systematic review of existing literature. A cluster of ED visits for asthma was identified in close proximity to the coal-fired power plants in the Wabamum area; however, similar clustering was not identified in close proximity to Alberta’s Industrial Heartland. Conclusions: There are two key factors that potentially explain these results: the decreased ED visit rates for children with acute asthma and the decreased concentration and variability of air pollutants, compared to reports in the previous decade. The decreased ED visits may be explained, in part, by improved access to primary care and changes in asthma management over time. This dissertation results add to the available literature by suggesting that there might be children’s health benefits associated with better air quality conditions and adverse effects of industrial pollution from coal-fired power plants on hospital ED visits for asthma in children.

  • Subjects / Keywords
  • Graduation date
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.