Long-term exposure to three common air pollutants — fine particulate matter, nitrogen dioxide, and ozone — were not found to be “convincingly” linked to incidence of multiple sclerosis (MS) in a large population study conducted in Canada.
The study, “Long-term exposure to air pollution and the incidence of multiple sclerosis: A population-based cohort study,” was published in the journal Environmental Research.
A person’s genes are known to affect MS risk, as do environmental conditions. Among the latter, exposure to ambient air pollution is thought to possibly heighten inflammation and oxidative stress — an imbalance between the body’s production of potentially harmful reactive oxygen species and its ability to contain them.
Recent studies have suggested that pollutants in the air can cross the blood-brain barrier, entering the brain and damaging the central nervous system, and to progress certain neurological disorders. In fact, the study points to associations made in previous research to such diseases as Parkinson’s, dementia, and cardiovascular and pulmonary disorders.
It notes that very few studies have looked into possible links between airborne environmental pollutants and MS incidence, despite the high level of MS across North America.
Among the most harmful types of air pollutant are fine particulate matter — microscopic particles resulting from natural or human causes — and gases such as nitrogen dioxide and ozone.
The effects of ambient air pollution on MS are still controversial. Clinical data has linked daily increases of such pollutants to elevated daily rates of MS relapse, while other studies have found no association between MS and long-term exposure to these pollutants.
Researchers investigated the association between MS incidence and long-term exposure to three common airborne pollutants — fine particulates with a diameter of 2.5 micrometers (PM2.5), nitrogen dioxide (NO2) and ozone (O3) — in a large study of residents of Ontario.