title: Potential impact of air pollution on multiple sclerosis in Tehran, Iran.
abstract: BACKGROUND
  Multiple sclerosis (MS) incidence has dramatically increased in Tehran, Iran. The health impact of air pollution in Tehran underscores the attention to a possible association to this environmental risk factor. In this study, the authors aimed to analyze the spatial distribution of prevalent MS cases and their association with the spatial patterns of air pollution.
  
  
  METHODS
  Patient records meeting McDonald's criteria for definite MS diagnosis with disease onset during 2003-2013 were obtained. Next, the location of 2,188 patients was successfully geo-referenced within Tehran metropolis by geographic information system (GIS) bureau of Iran's post office based on their phone numbers. A cluster analysis was performed using the average nearest neighbor index (ANNI) and quadrat analysis. The long-term exposures of MS patients to particulate matter (PM10), sulfur dioxide (SO2), nitrogen oxide (NO), nitrogen dioxide (NO2), and nitrogen oxides (NOx) were estimated using the previously developed land use regression models.
  
  
  RESULTS
  Prevalent MS cases had a clustered pattern in Tehran. A significant difference in exposure to PM10, SO2, NO2, and NOx (p < 0.001) was observed in MS cases compared with controls.
  
  
  CONCLUSIONS
  This study revealed the potential role of long-term exposure to air pollutants as an environmental risk factor in MS.
authors.affiliation: MS Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Pouria
authors.initials: P
authors.lastname: Heydarpour
authors.forename: Hassan
authors.initials: H
authors.lastname: Amini
authors.forename: Shayan
authors.initials: S
authors.lastname: Khoshkish
authors.forename: Hossein
authors.initials: H
authors.lastname: Seidkhani
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Sahraian
authors.forename: Masud
authors.initials: M
authors.lastname: Yunesian
mesh_terms: D000397:Air Pollution / Q000009:adverse effects*; D016000:Cluster Analysis; D004781:Environmental Exposure / Q000009:adverse effects*; D062305:Geographic Mapping; D006801:Humans; D007492:Iran; D009103:Multiple Sclerosis / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D012307:Risk Factors