RT Journal Article
SR Electronic
T1 Comparison of childhood asthma incidence in 3 neighbouring cities in southwestern Ontario: a 25-year longitudinal cohort study
JF CMAJ Open
JO CMAJ
FD Canadian Medical Association
SP E433
OP E442
DO 10.9778/cmajo.20200130
VO 9
IS 2
A1 Dhenuka Radhakrishnan
A1 Sarah E. Bota
A1 April Price
A1 Alexandra Ouédraogo
A1 Murad Husein
A1 Kristin K. Clemens
A1 Salimah Z. Shariff
YR 2021
UL http://www.cmajopen.ca/content/9/2/E433.abstract
AB Background: Air pollution is a known trigger for exacerbations among individuals with asthma, but its role in the development of new-onset asthma is unclear. We compared the rate of new asthma cases in Sarnia, a city with high pollution levels, with the rates in 2 neighbouring regions in southwestern Ontario, Canada.Methods: Using a population-based birth cohort design and linked health administrative data, we compared the hazard of incident asthma among children 0 to 10 years of age between those born in Lambton (Sarnia) and those born in Windsor and London–Middlesex, for the period Apr. 1, 1993, to Mar. 31, 2009. We used Cox proportional hazards models to adjust for year of birth and exposure to air pollutants (nitrogen dioxide, sulphur dioxide [SO2], ozone and small particulate matter [PM2.5]), as well as maternal, geographic and socioeconomic factors.Results: Among 114 427 children, the highest incidence of asthma was in Lambton, followed by Windsor and London–Middlesex (30.3, 24.4 and 19.8 per 1000 person-years, respectively; p < 0.001). Relative to Lambton, the hazard of asthma, adjusted for socioeconomic and perinatal factors, was lower in Windsor (hazard ratio [HR] 0.72, 95% confidence interval [CI] 0.67–0.77) and London–Middlesex (HR 0.65, 95% CI 0.61–0.69). Inclusion of air pollutants attenuated this relative difference in both Windsor (HR 0.79, 95% CI 0.62–1.01) and London–Middlesex (HR 0.89, 95% CI 0.64–1.24).Interpretation We identified a higher incidence of asthma among children born in Lambton (Sarnia) relative to 2 other regions in southwestern Ontario. Higher levels of air pollution (particularly SO2 and PM2.5) in this region, as experienced by children in their first year of life, may be contributory.