Exposure to air pollutants, particularly to fine particle pollutants (2.5 micrometers or less in diameter), seems to increase a person’s risk of multiple sclerosis (MS), a study from northern Italy suggests.
It found that people living in urban, more polluted areas have a 16% higher relative risk of developing this disease than do people in rural areas.
These findings were disclosed at the 2020 European Academy of Neurology (EAN) Congress — held virtually due to the COVIV-19 pandemic — in the oral presentation “PM2.5 exposure is a risk factor of multiple sclerosis. An ecological study with a Bayesian mapping approach” (registration at EAN is needed to access its studies).
Many environmental factors are known to act as triggers of the damaging immune response seen in MS patients. Those most well-studied include cigarette smoking, diet, and levels of vitamin D. But exposure to air pollutants has also been suggested as a risk factor.
Professor Roberto Bergamaschi and his team at the Instituto Neurologico Nazionale a Carattere Scientifico (IRCCS) examined the exposure to air pollutants among a group of 927 MS patients in northern Italy.
Patients were from the province of Pavia, which includes 188 municipalities, and were specifically examined for their exposure to fine particulate matter smaller than 2.5 micrometers in diameter (known as PM2.5).
These particles are a mixture of solid and liquid matter suspended in air, that arise mainly from household and commercial heating, industrial activities, roadway vehicles, and agriculture. The analysis was conducted during the winter, which is when pollutant concentrations reach higher levels.
The team noted that Pavia could be divided into three separate air pollution zones, with the northern region — which borders the urbanized Milan area — having the highest seasonal levels of PM2.5, with concentrations progressively decreasing as you move south. Cases of MS also appeared to be less common in this province’s southern region.