An Investigation of the Association between Maternal and Early Life Exposure to Urban Greenness and the Incidence of Childhood Asthma

Several epidemiological studies have investigated the possible role that living in areas with greater amounts of greenspace has on the development of childhood asthma. These studies have yielded inconsistent findings, and not all have explored the relevance of timing of exposure. This topic was studied using a retrospective cohort study design that consisted of 982,131 singleton births in Ontario, Canada between 2006 and 2013. Two measures of greenness, NDVI and GVI, were assigned to the residential area. Asthma diagnoses were determined by using administrative data. The Cox proportional hazards model was used to characterize associations between greenness measures and asthma (up to age 12 years) while adjusting for several risk factors. This thesis suggests that greenness is not associated with the development of asthma. However, greenness may reduce the risk of developing asthma for children diagnosed at older age, and for those children born during the spring and summer seasons.