Long-term exposure to air pollution, specifically sulfur dioxide (SO₂), is associated with a higher risk of amyotrophic lateral sclerosis (ALS).[1][2] This is the first study to document that higher SO₂ levels in residential areas are associated with an increased risk of ALS.[1] For an increase in SO₂ exposure of 0.14 ppb, the probability of an ALS diagnosis increased 1.23 times.[1][2] This association was significant for SO₂ exposure five to ten years prior to disease onset.[1] Conversely, exposure to other types of air pollution—nitrogen dioxide (NO₂), ground-level ozone (O₃), and fine particulate matter PM2.5—was not associated with ALS.[1] The researchers emphasize that the relationship between SO₂ and ALS is not linear, meaning that a doubling of SO₂ exposure may not double the risk of ALS.[1] The findings support the need for improved air pollution control measures.[1][2]