Long-term air pollution exposure may increase risk of developing MS: Study
Short-term exposure associated with worsened disease activity, disability
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Panoramic view of an urban power plant with multiple tall chimneys and cooling towers emitting thick plumes of smoke.
- Long-term exposure to air pollution, especially particulate matter, significantly increases the risk of MS.
- Short-term air pollution exposure worsens MS activity, including relapses, lesions, and disability progression.
- Reducing air pollution levels is a key strategy for protecting brain health and managing multiple sclerosis.
Long-term exposure to air pollution may increase the risk of developing multiple sclerosis (MS), while short-term exposure may worsen disease activity and disability in people who already have the condition, according to a new study.
“Long-term air pollution exposure was associated with higher MS risk, and short-term exposure with greater disease severity,” researchers wrote, adding that these data indicate that “reducing air pollution may be a key strategy to protect brain health in MS.”
The findings come from a systematic review and meta-analysis, “Air Pollution and the Risk and Progression of Multiple Sclerosis: A Systematic Review and Meta-Analysis,” which was published in the Annals of Clinical and Translational Neurology.
Researchers: Global efforts needed to reduce air pollution levels
Air pollution is known to have a wide range of adverse health consequences and has been linked to several neurological conditions, including Parkinson’s disease and dementia. Previous studies have also suggested that air pollution may increase the risk of developing MS and influence the disease’s progression, but this association is less certain.
To learn more, two U.S.-based researchers reviewed the available scientific literature and pooled data from eligible studies that have examined this connection. Their analysis included 22 studies involving more than 16 million people.
The results showed that long-term exposure to particulate matter — tiny particles of dust, dirt, or smoke suspended in the air — was significantly associated with a higher risk of developing MS. This was true for particulate matter smaller than 2.5 micrometers, which increased the risk of MS by 21%, and for particulate matter smaller than 10 micrometers, which increased the risk by 20%.
Long-term exposure to other airborne chemicals, such as carbon monoxide, sulphur dioxide, and ozone, which are generated mainly by fossil fuel combustion and traffic-related emissions, was not significantly associated with an increased risk of developing MS.
Our study provides strong evidence of the association between air pollution and risk of developing MS and severity of MS including relapses, developing [active lesions], and disability progression.
Among people already diagnosed with MS, available studies indicated that short-term exposure to particulate matter was significantly associated with relapses, lesions with active inflammation, and disability progression.
Short-term exposure to nitrogen dioxide and ozone was also linked with relapse risk among MS patients, while short-term exposure to sulphur dioxide and ozone was significantly associated with disability progression.
“Our study provides strong evidence of the association between air pollution and risk of developing MS and severity of MS including relapses, developing [active lesions], and disability progression,” the scientists wrote.
The scientists noted a few limitations to this analysis. Most studies were conducted in Europe or the Americas, making it difficult to extrapolate findings to other parts of the world. Also, some analyses indicated substantial heterogeneity — meaning that different studies yielded divergent results, making conclusions from these analyses less certain.
Finally, the researchers weren’t able to fully account for factors like socioeconomic status that may influence both pollution exposure and healthcare outcomes.
While more studies are needed to fully understand the relationship between MS and air pollution, “global efforts and policies are needed to reduce and combat air pollution levels to reduce the burden of MS among other neurological and non-neurological diseases,” the researchers said.
