Association of Air and Noise Pollution with Unprovoked Seizures and New-Onset Epilepsy

Air and noise pollution have been associated with the onset and symptoms of many health conditions, but its association with unprovoked seizures and new-onset epilepsy is unclear. The objectives of this thesis were to: (1) synthesize the literature examining associations between short- and long-term exposure to outdoor air and noise pollution and the risk of unprovoked seizures and new-onset epilepsy; and estimate the risk of new-onset epilepsy associated with long-term outdoor exposure to (2) fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ground-level ozone (O3), and (3) road traffic noise. We addressed Objective 1 using a systematic review and meta-analysis, including observational and ecological studies assessing the associations of air and noise pollution with unprovoked seizures and new-onset epilepsy. We addressed Objectives 2 and 3 using population-based nested case-control studies, including adults residing in Ontario as of January 1, 2010, without a history of epilepsy. Air and noise pollution were measured using three-year averages of the annual average PM2.5, NO2, and O3 concentrations, and the 8-hour nighttime, 16-hour daytime, and 24-hour road traffic noise levels, at the participant’s residence. We included only one study in the systematic review and meta-analysis that estimated the association of air pollution with new-onset epilepsy. No studies estimated the associations of noise pollution with either unprovoked seizures or new-onset epilepsy. We included 16 studies of the association of air pollution with unprovoked seizures, eight of which were synthesized quantitatively. We found that short-term exposure to O3 may reduce the risk of unprovoked seizures, and short-term exposure to NO2 and carbon monoxide may increase this risk. When estimating the association of air pollution with new-onset epilepsy, we found positive associations for O3 and PM2.5, and a negative association for NO2. When estimating the association of road traffic noise with new-onset epilepsy, we found positive but statistically insignificant associations with the 8-hour nighttime and 24-hour daytime estimates. Although additional research is needed, these findings indicate that air and noise pollution may be potential interventional targets to prevent the onset of epilepsy and improve patient quality of life.