• Posted January 21, 2026

Air Pollution Increases Risk Of ALS

Prolonged exposure to air pollution appears to increase a person’s risk of ALS and other motor neuron diseases, a new study says.

Further, air pollution also appears to speed up the disease in people diagnosed with ALS, researchers reported Jan. 20 in JAMA Neurology.

“Our results suggest that air pollution might not only contribute to the onset of the disease, but also affect how quickly it progresses,” researcher Dr. Caroline Ingre said in a news release. She's an adjunct professor of clinical neuroscience at the Karolinska Institute in Sweden.

For the study, researchers analyzed the air pollution exposure of 1,463 people with Sweden with recently diagnosed motor neuron diseases, comparing them against nearly 1,800 siblings and more than 7,000 healthy people.

Motor neuron diseases damage the nerve cells that govern voluntary movement, leading to muscle atrophy and paralysis, researchers said in background notes. 

Amyotrophic Lateral Sclerosis, or ALS, is the most common type, accounting for up to 90% of cases.

Long-term exposure to air pollution — even at the relatively low levels found in Sweden — was associated with a 20% to 30% increased risk of motor neuron diseases like ALS, researchers reported.

They also found that higher levels of air pollution were associated with faster functional decline and a greater risk of death after diagnosis with a motor neuron disease.

“We can see a clear association, despite the fact that levels of air pollution in Sweden are lower than in many other countries,” said lead investigator Jing Wu, a postdoctoral researcher at Karolinska’s Institute of Environmental Medicine. “This underlines the importance of improving air quality.”

The study wasn’t designed to explore the causes of this association, but researchers noted that air pollution can cause inflammation and oxidative stress in the nervous system.

Dr. Jacqueline Moline, senior vice president and chair of occupational medicine, epidemiology and prevention at Northwell Health in Manhasset, New York, told HealthDay that the results are “more dramatic” given they were found in a country with relatively clean air.

"Not only are we concerned that if you're in areas that have higher air pollution, you're at increased risk of developing the disease, but once you develop it, if that air pollution persists, then it's associated with a worse outcome," Moline said.

She agreed with the researchers’ speculation that inflammation underlies this effect.

“We know that air pollution and the chemicals that are found in air pollution are pro-inflammatory,” Moline said. "They’re breathed in, the particles get into the lung, and some of these can cause changes in the neurons, the cells that are responsible for movement and thinking. There's some evidence that this inflammatory cascade, as it starts, can affect the brain and central nervous system."

She said people might be able to lower their risk by avoiding the outdoors on days when the skies are choked with smog.

“On those days where there's poor air quality, make sure you limit the amount of time you spend outside or exercising," Moline added.

More information

The ALS Association has more on Amyotrophic Lateral Sclerosis.

SOURCES: Karolinska Institute, news release, Jan. 20, 2026; Interview with Dr. Jacqueline Moline, senior vice president and chair, occupational medicine, epidemiology and prevention, Northwell Health