Research Shows Air Pollution Can Be a Possible Trigger for Multiple Sclerosis Relapse

A team of investigators is using an urban air dispersion model known as the Atmospheric Dispersion Modeling System to evaluate various measurements of air pollution, land and surface roughness, and emission inventories.

For anyone with multiple sclerosis, relapse episodes come and go at random, along with periods of remission. It can come at any time and doctors really know how they can be prevented, besides taking the prescribed medications. When they occur, relapses can be scary and debilitating, possibly landing an unwanted trip to the hospital. Not only can it be difficult to go about daily activities, but it can also be very distressing and painful.

The French School of Public Health took up a task of trying to study the connection between environmental factors and multiple sclerosis. Atmospheric Dispersion Modeling System was used by the team of investigators. This was to evaluate the measurement of land, air pollution, emission inventories and surface roughness. They wanted to find out how relapse of multiple sclerosis could happen due to air pollution. This is because in patients with MS they have seen seasonal patterns and variations. Not many studies have been done to study their correlation and those that tried studying the correlation were flawed since the methods had limitations. Although some significant correlation was found by few studies but the findings became less convincing due to the limitations.

A case-crossover study was done by the French School of Public Health. 536 multiple sclerosis patients were evaluated and from 2000-2009 they were followed. In Strasbourg, France these patients were identified to be using regional Multiple Sclerosis Network. For relapse occurrence they were monitored and over a period of this time a total of 2052 relapse occurrences were recorded. These patients were differentiated by the researchers based on socioeconomic characteristics.

Even the air particulates in the environment where they lived were measured. Particles of size less than 10um were tracked and they recorded the level of pollutants. Particles of this size can easily get through the natural defence system of our body. Then the investigators juxtaposed several occurrences of relapses with levels of air particulate matter. For each residential block where the study patients were residing hourly data was recorded. Also the variability in warm and cold season atmospheric pressure measurements, humidity, weekly influenza reports and daily pollen counts within each place was recorded.

It was found that over the course of the study period 2052 episodes of relapses occurred. Out of these, during cold season 1009 relapses occurred, during hot seasons 1043 relapses occurred.  Within the stratification the mean age of MS onsets or the sex ratio was no different although the patients were characterized by socioeconomic conditions. It was found that between air pollutants and relapse there was a correlation however it was during the cold season it was surprisingly more. In the hot season it was less powerful. Also the relapse was found to be associated with pollen levels but this association was found only during the hot season. Also between influenza reports and higher level of relapse during the cold season positive correlation was found.

On both ends of the financial spectrum some correlation was found between in terms of the socioeconomic status of the patients that were followed. For both the poorest and the wealthiest the relapse rate was higher. The relation between MS and environment seems to get more complicated. According to the data the risk of MS increases due to air pollution and other environmental factors. Another new observation was the variability seen based on socioeconomic status. MS influences by a complex web of environmental factors are reflected by these findings. This study helps the MS patients to know how their health can be influenced by their work environmental or living situation. Thus the disease can be prevented from becoming worse by avoiding potential triggers.