An impact of air pollution on moderate to severe relapses among multiple sclerosis patients

Miri Elgabsi, Lena Novack, Shaked Yarza, Matan Elgabsi, Alexandra Shtein, Gal Ifergane

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Background: Multiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system with both a genetic and environmental component. Objective: In the current study, we examined an association between incidence of MS moderate to severe relapses and exposure to air pollutants and meteorological exposures. Methods: We enrolled MS patients in Southern Israel during 2000-2017. Exposure assessment relied on satellite-based model of exposure to particulate matter of size <2.5 and 10 microns (PM2.5, PM10) and temperature at a spatial resolution of 1 km (Kloog et al., 2015). The information on exposure to nitrogen dioxide (NO2), sulfur dioxide (SO2) and ozone (O3) levels was completed from the database of the monitoring stations. We analyzed the data using a semi-ecological approach. The monthly incidence of MS-related relapses requiring hospitalization as a function of environmental factors was analyzed by time-series technique, adjusting to sex, age and smoking. We also used a case-crossover approach to compare environmental exposure of a patient on the day of the relapse with the exposure on the relapse-free days. All estimates were adjusted to the heat index and were divided by IQR. Results: There were 287 MS patients in the study, with an average age of 52.8 ± 16.7 years, 37% of them (107) being under 40. Mostly female (66.2%), and 13.6% of the patients smoking (47% non-smoking and 39.4% unknown). PM2.5 was independently associated with MS relapses within the non-smoking population [Relative Risk (RR)=1.28, 95%CI:1.01-1.62]. O3 was found adversely associated with MS relapses among patients younger than 40 [RR=1.58, 95%CI 1.03-4.43]. Based on the case-crossover approach, relapses were associated with elevated levels of PM10 and NO2 in all subjects [Odds Ratio (OR)=1.05, 95%CI:1.00-1.11; OR=1.85, 95%CI: 1.28-2.68, respectively]. An adverse association with PM2.5 was observed in non-smokers [OR 1.12, 95%CI 1.00-1.25]. Conclusions: The findings show that MS relapses are adversely associated with an ambient exposure to PM and NO2.

Original languageEnglish
Article number103043
JournalMultiple Sclerosis and Related Disorders
StatePublished - 1 Aug 2021


  • Air pollution
  • Case crossover
  • Environment
  • Multiple sclerosis
  • PM

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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