ICES research video series: Li Bai on diabetes, hypertension risk & exposure to ultrafine particles
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ICES research video series: Li Bai on diabetes, hypertension risk & exposure to ultrafine particles

September 9, 2019


My name is Li Bai, I am a epidemiologist at
the Institute for Clinical Evaluative Sciences in Toronto Canada. On behalf of
the research team I’m happy today to talk to you about the abstract. Previous studies have found that
long-term exposure to air pollutants such as nitrogen dioxide may increase
the incidence of hypertension and diabetes. However, little is known about the
impacts of ultrafine particles. Ultrafine particles are the smallest of particles
in the air and mainly come from diesel vehicles in urban areas. Our study population includes all Canadian-born residents age 30 to 100 years old who lived in the City of Toronto from 1996 to 2012. Our final cohorts included almost 1 million people. We used a validated
algorithm to link province-wide chronic disease databases to determine our study
outcomes. We estimated annual concentrations of ultrafine particles and nitrogen dioxide using land use regression models based on monitoring
data, and then we assigned these estimates to individuals annual postal codes
during the follow-up. To evaluate the associations we used random effects
Cox proportional hazards models, with an adjustment for both individual- and
neighborhood-level risk factors. We found each interquartile increase in
ultrafine particles was associated with a 3% increased risk for hypertension
incidence, and a 6% increase in the risk for diabetes incidence, even after adjusting
for fine particles and nitrogen dioxide. We also observed that exposure to nitrogen
dioxide may increase the risk of diabetes incidence. A main strength of this study is our
ability to categorize the associations between long-term exposure to ultrafine
particles and the development of hypertension and diabetes over 17 years
of follow-up. However, similar to other large cohort studies, we were unable to
directly adjust for some individual level risk factors. To our knowledge, this is the first
population-based cohort study to investigate the association between
long-term exposure to ultrafine particles and the development of
hypertension and diabetes and we did find a positive association.

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