Residential Sulfur Dioxide Exposure Associated with Increased Risk of ALS Onset

Recent research by scientists from Université de Sherbrooke and Canadian collaborators has highlighted a potential environmental risk factor for amyotrophic lateral sclerosis (ALS), a devastating neurodegenerative disease. The study found that long-term residential exposure to sulfur dioxide (SO₂), a common air pollutant, is linked to higher odds of developing ALS.

ALS is a rare but severe motor neuron disease characterized by progressive muscle weakness, leading to paralysis and death within a few years of diagnosis. Although the exact causes of ALS remain unknown, environmental factors such as air pollution have been increasingly studied for their potential role in disease onset.

Sulfur dioxide primarily originates from the burning of fossil fuels, particularly in power plants and diesel vehicles. Despite its presence in the environment, the association between SO₂ exposure and neurodegenerative diseases like ALS has not been extensively explored.

In this case-control study published in "Environmental Research," researchers analyzed data from 304 ALS patients and 1,207 matched controls in New Brunswick, Canada. They used postal-code linked estimates to assess individual exposure levels to multiple pollutants, including nitrogen dioxide (NO₂), ozone (O₃), particulate matter (PM₂.5), and SO₂, focusing on the period before disease onset.

The results indicated that individuals diagnosed with ALS had higher median residential SO₂ levels compared to controls. Specifically, an increase in SO₂ exposure by 0.14 parts per billion (ppb) was associated with a 23% higher risk of developing ALS (odds ratio of 1.23). Notably, other pollutants like NO₂, O₃, PM₂.5, and smoke did not show significant associations in adjusted models.

The relationship persisted even when analyzing exposure windows of five and ten years prior to diagnosis, reinforcing the potential role of SO₂ in ALS development. Researchers emphasize that these findings suggest the need for stricter air pollution controls to potentially reduce ALS risk.

While further studies are necessary to confirm these results, this research contributes to a growing body of evidence linking air quality to neurodegenerative diseases. Public health strategies aimed at reducing sulfur dioxide emissions could be a crucial step in lowering ALS incidence and protecting neurological health.

Published on September 30, 2025, and reviewed by experts in the field, this study underscores the importance of environmental factors in neurological disease etiology. For more detailed information, consult the original publication: [Environmental Research, DOI: 10.1016/j.envres.2025.122232].