Associations between long-term air pollution exposure and the development of amyotrophic lateral sclerosis: A matched case-control study.

There is increasing evidence of an association between air pollution, particularly nitrogen dioxide (NO2), and the development of amyotrophic lateral sclerosis (ALS). However, investigation into sulfur dioxide (SO2) remains understudied. Also, empirical identification of confounding variables to adjust for in ALS environmental studies is largely absent. Thus, we created a multifactorial database, mapped hypothesized direct effects of air pollutants, and conducted a matched case-control study in New Brunswick, Canada to investigate the association between long-term exposure to various air pollutants and the development of ALS. Odds of ALS onset was significantly associated with increased SO2 exposure (OR = 1.23; 95 % CI: 1.02-1.47, per IQR increase of 0.14 ppb) in adjusted direct effect models, but not associated with exposure to NO2 (OR = 1.09; 95 % CI: 0.87-1.41, per IQR increase of 2.79 ppb), ozone (O3) (OR = 0.99; 95 % CI: 0.80-1.22, per IQR increase of 2.31 ppb), fine particulate matter (PM2.5) (OR = 0.99; 95 % CI: 0.80-1.23, per IQR increase of 0.52 μg/m3) or PM2.5(smoke) (OR = 1.05; 95 % CI: 0.83-1.35, per IQR increase of 0.68 μg/m3). As for recency models, SO2 remained significantly associated with ALS in both 5-year (OR = 1.21; 95 % CI: 1.03-1.43) and 10-year prior to onset sensitivity models (OR = 1.23; 95 % CI: 1.02-1.47). Our findings support the association between long-term exposure to air pollutants, particularly SO2, and the development of ALS, supporting the need for improved air pollution control measures.