#MSPrevention: air pollution

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Barts-MS rose-tinted-odometer: ★★

As MS is highly likely to be a preventable disease we should be doing everything we can to reduce our exposure to modifiable risk factors. Smoking, passive smoking, solvent exposure and air pollution have all been linked to an increased incidence of MS. It has always been argued that air pollution may work by acting as a filter for ultraviolet light and hence increases one’s risk of getting MS by reducing UVB exposure, which is important for vitamin D synthesis in the skin. However, I am not sure this is the case as common to all these exposures, including air pollution, is inflammation in the lungs. 

The current hypothesis is that inflammation in the lungs changes or alters proteins via a process called post-translational modification, which converts normal proteins in highly immunogenic autoantigens that trigger autoimmune disease. There is good support for the latter hypothesis in rheumatoid arthritis, but to the best of my knowledge outside of animal models, the evidence in MS remains speculative. Saying this who wouldn’t want to breathe clean air if one of the benefits is a lower risk of MS? 

The study below from Padua Province in Italy shows quite a strong correlation (r-0.89) between exposure to particulate matter in the air greater than 2.5  micrometres (PM2.5) and the prevalence of MS. Some epidemiologists say that when you start seeing R-values close to 0.9 it is hard to ignore them and suggest the relationship could be causal. I am not sure about this, but it is clear that we need to more interventional studies, to reduce air pollution, and track what happens to MS incidence. 

Air pollution over London.

In relation to the issue of air quality, there was a landmark ruling from an inquest yesterday that linked the tragic death of a nine-year-old girl, Ella Adoo-Kissi-Debrah, who died following an asthma attack 9 years ago to air pollution. Legal pundits have stressed the importance of this case, which will now create the legal precedent for the UK to modify its clean air act. The importance of the latter cannot be ignored as it may lead to a drop in the incidence of many diseases linked to air pollution including MS. 

The question we also need to ask ourselves is there anything we can do to address the problem of air pollution in low- and middle-income countries that are all seeing a rise in MS incidence? Let’s hope as we transition from a carbon-energy economy to other cleaner forms of energy we will see this problem improve across the world.

Arianna et al. Association of Multiple Sclerosis with PM 2.5 levels. Further evidence from the highly polluted area of Padua Province, Italy.  Mult Scler Relat Disord. 2020 Dec 6;48:102677. doi: 10.1016/j.msard.2020.102677. Online ahead of print.

Background: Fifty years of epidemiological survey and intra-regional differences in prevalence suggest that environmental factors may be associated with increased multiple sclerosis (MS) risk in Northern Italy. Based on the findings of a previous study carried out in the highly polluted Padan Plain, we further explored the relationship between PM2.5 levels and MS prevalence by comparing bordering areas characterized by quite different environmental conditions, namely the Municipality of Padua and the special protected zone (SPZ) of the Euganean Hills Regional Park, located 15 km from the City.

Methods: Three territories were identified; 1) the SPZ, extending over an area of 15.096 hectares and having a total population of 23,980 inhabitants, 2) the urban area of Padua, with a total population of 210,440 inhabitants and repeatedly recognized by the European Environmental Agency as one of the most polluted cities of Europe, 3) the Intermediate Zone (IZ), i.e., the area in between the previous two, including part of the urban territories of eight villages adjacent to the SPZ. Demographic and socio-economical data were obtained from official government sources (www.istat.it and http://www.regione.veneto.it). All Italian MS patients residing in these three areas on December 31, 2018, were registered. PM2.5 concentrations (annual average 1998-2018, μg/m3) were measured by satellite. The correlation between PM2.5 concentrations and MS prevalence was analysed.

Results: MS prevalence was significantly higher in Padua City (265/100.000) compared to both the SPZ of the Euganean Hills Park (160/100,000; p < 0.0001) and the IZ (194.4/100,000). Prevalence strongly associated with the annual average concentration of PM2.5 (r = 0.89 p < 0.00001).

Conclusion: In the Province of Padua, one of the most polluted areas of Europe, MS prevalence is strongly associated with PM2.5 exposure. Our findings suggest that air pollutants may be one of the possible environmental risk factors for MS in the Veneto Region of Italy.

Crowdfunding: Have you supported Prof G’s ‘Bed-to-5km Challenge’ yet? Please do, all the money collected is going towards supporting MS research. 

CoI: multiple

Twitter: @gavinGiovannoni                                              Medium: @gavin_24211

About the author

Prof G

Professor of Neurology, Barts & The London. MS & Preventive Neurology thinker, blogger, runner, vegetable gardener, husband, father, cook and wine & food lover.

14 comments

  • I worked on atmospheric pollution for a few years. For sure it is not good for health but I learned that the air today is cleaner than in 1970-1990. Also if you think back to the ancient cities where heating was based on wood and coal combustion you would easily understand how much more polluted the air was then. Also the fires where burnt in the middle of the room with poor air exchange with outdoor. Therefore I would have expected to see a much higher level of MS in the past years if air pollution was involved.
    Basically what we really know is that MS has the highest prevalence in rich countries where indeed there is air pollution but there is also the largest use of chemicals, soaps, technological materials, meat consumption and other things. Japan is an example of the latter. But if we are worried about post translational modification also seaside locations should have somewhat higher MS incidence as in the sea spray there are substances capable to modify proteins. These substances are like formaldehyde and they are very diffuse in nature and they are not monitored by any regulation but they are there and they are dangerous probably even more than PM.
    In the end I don’t think it’s pollution… if I would have to place a bet I would bet on mammalian meat consumption. I feel there is more biology on this than on air pollution.

    • Maybe there is a time factor… people who breathed the polluted air when they were young in the 1970-90s are now getting diagnosed with MS?

      • Incidence is rising almost everywhere and some countries have better air quality than 50 years ago so I am not sure this is an explanation for young people being diagnosed more and more now…

          • ….. in the cars and not only sunscreens… make up independent of the presence of sunscreens in it 😉 pollution in general is a screen for uv light.
            Beside the sun exposure, also indoor air quality may not be very good….
            Coming back to the paper, in Padua in 2018 they had 30 days where the weather was foggy for at least 6 hours a day. On average they have 7 sunny hours a day through the year. Not so much sun. The other territories mentioned in the paper are made of hills where there is less fog and the sun is better so I would say that in this case the sun makes the difference in the data. I wonder if sun only makes vitamin D and no other compounds we are not aware of….

          • We are staying indoors now more due to the pandemic. Add the increase in use of technology and decrease of outdoor activity in the younger generation. We might have a epidemic as posted earlier.

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