Thesis Abstract

Abstract
Childhood asthma is a significant public health concern worldwide, with environmental factors playing a crucial role in its development. Among environmental factors, air pollution has been identified as a key contributor to the increasing prevalence of childhood asthma. This study aimed to investigate the effect of early life exposure to air pollution on the development of childhood asthma. A comprehensive literature review was conducted to examine existing research on the relationship between early life exposure to air pollution and childhood asthma. The review included studies that explored different types of air pollutants, such as particulate matter (PM), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3), and their impact on asthma development in children. The findings revealed that early life exposure to air pollution is significantly associated with an increased risk of developing childhood asthma. Several studies reported a positive correlation between exposure to air pollutants and the incidence of asthma symptoms, such as wheezing, coughing, and shortness of breath in children. Additionally, exposure to air pollution during pregnancy and early childhood was found to be particularly detrimental to lung development and respiratory health, leading to long-term consequences for asthma risk. Furthermore, the review highlighted the importance of considering the timing, duration, and intensity of air pollution exposure in relation to asthma development. Prenatal exposure to air pollutants was shown to have a lasting impact on lung function and immune responses in children, predisposing them to asthma later in life. Moreover, early childhood exposure to air pollution was associated with persistent asthma symptoms and exacerbations, emphasizing the need for early interventions to mitigate the effects of air pollution on respiratory health. In conclusion, this study underscores the critical role of early life exposure to air pollution in the development of childhood asthma. The findings suggest that reducing air pollution levels, especially during sensitive periods of development, may help prevent the onset of asthma and improve respiratory outcomes in children. Public health policies aimed at reducing air pollution and promoting clean air initiatives are essential for protecting children's respiratory health and reducing the burden of childhood asthma.

Thesis Overview

There is increasing recognition of the importance of early environmental exposures in the development of childhood asthma. Outdoor air pollution is a recognized asthma trigger, but it is unclear whether exposure influences incident disease. We investigated the effect of exposure to ambient air pollution in utero and during the first year of life on risk of subsequent asthma diagnosis in a population-based nested case-control study.

METHODS:

We assessed all children born in southwestern British Columbia in 1999 and 2000 (n = 37,401) for incidence of asthma diagnosis up to 34 years of age using outpatient and hospitalization records. Asthma cases were age- and sex-matched to five randomly chosen controls from the eligible cohort. We estimated each individual’s exposure to ambient air pollution for the gestational period and first year of life using high-resolution pollution surfaces derived from regulatory monitoring data as well as land use regression models adjusted for temporal variation. We used logistic regression analyses to estimate effects of carbon monoxide, nitric oxide, nitrogen dioxide, particulate matter RESULTS:

A total of 3,482 children (9%) were classified as asthma cases. We observed a statistically significantly increased risk of asthma diagnosis with increased early life exposure to CO, NO, NO2, PM10, SO2, and black carbon and proximity to point sources. Traffic-related pollutants were associated with the highest risks: adjusted odds ratio = 1.08 (95% confidence interval, 1.041.12) for a 10-microg/m3 increase of NO, 1.12 (1.071.17) for a 10-microg/m3 increase in NO2, and 1.10 (1.061.13) for a 100-microg/m3 increase in CO. These data support the hypothesis that early childhood exposure to air pollutants plays a role in development of asthma.