UVR and vitamin D seem to affect MS risk in adults independently of HLA-DRB1*15 status. UVR exposure may also exert a protective effect against developing MS via other pathways than those involving vitamin D.

From a public health perspective, the impact of smoking and passive smoking on MS risk is considerable. Preventive measures in order to reduce tobacco smoke exposure are, therefore, essential. In particular, individuals with a history of MS in the family should be informed regarding the impact of smoking on the risk of MS, and the importance of preventing their children from being exposed to passive smoke.

The presence of lipid-specific immunoglobulin M bands in CSF predicts a more adverse long-term outcome in patients with MS; it may thus define a subset of patients who might benefit from aggressive treatment during the early phase of the disease.

Exposure to environmental tobacco smoke is associated with an increased risk for multiple sclerosis. Since smoking, but not usage of oral tobacco in the form of moist snuff, is associated with increased risk for multiple sclerosis, we consider that the critical effects of passive smoking may be the result of irritations in the lungs. Hence, further studies would be valuable in order to clarify whether other forms of lung irritation, such as air pollution, contribute to the triggering of multiple sclerosis.