title: Impact of air pollution on pulmonary function and respiratory symptoms in children. Longitudinal repeated-measures study.
abstract: BACKGROUND
  Salamanca, Mexico occupied fourth place nationally in contaminating emissions. The aim of the study was to determine the impact of air pollution on the frequency of pulmonary function alterations and respiratory symptoms in school-age children in a longitudinal repeated-measures study.
  
  
  METHODS
  We recruited a cohort of 464 children from 6 to 14 years of age, from two schools differing in distance from the major stationary air pollution sources. Spirometry, respiratory symptoms and air pollutants (O3, SO2, NO, NO2, NOx, PM10,) were obtained for each season. Mixed models for continuous variables and multilevel logistic regression for respiratory symptoms were fitted taking into account seasonal variations in health effects according to air pollution levels.
  
  
  RESULTS
  Abnormalities in lung function and frequency of respiratory symptoms were higher in the school closer to major stationary air pollution sources than in the distant school. However, in winter differences on health disappeared. The principal alteration in lung function was the obstructive type, which frequency was greater in those students with greater exposure (10.4% vs. 5.3%; OR = 1.95, 95% CI 1.0-3.7), followed by the mixed pattern also more frequent in the same students (4.1% vs. 0.9%; OR = 4.69, 95% CI, 1.0-21.1). PM10 levels were the most consistent factor with a negative relationship with FVC, FEV1 and PEF but with a positive relationship with FEV1/FVC coefficient according to its change per 3-month period.
  
  
  CONCLUSIONS
  Students from the school closer to major stationary air pollution sources had in general more respiratory symptoms than those from the distant school. However, in winter air pollution was generalized in this city and differences in health disappeared. PM10 levels were the most consistent factor related to pulmonary function according, to its change per 3-month period.
authors.affiliation: Unidad Médica de Alta Especialidad No, 1, Instituto Mexicano del Seguro Social, López Mateos e Insurgentes s/n Col. Paraísos Z.C. 37320, León, México.
authors.forename: Benigno
authors.initials: B
authors.lastname: Linares
authors.forename: Juan M
authors.initials: JM
authors.lastname: Guizar
authors.forename: Norma
authors.initials: N
authors.lastname: Amador
authors.forename: Alfonso
authors.initials: A
authors.lastname: Garcia
authors.forename: Victor
authors.initials: V
authors.lastname: Miranda
authors.forename: Jose R
authors.initials: JR
authors.lastname: Perez
authors.forename: Rocío
authors.initials: R
authors.lastname: Chapela
mesh_terms: D000293:Adolescent; D000397:Air Pollution / Q000009:adverse effects*; D002248:Carbon Monoxide / Q000009:adverse effects; D002648:Child; D015331:Cohort Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008168:Lung / Q000503:physiopathology*; D008173:Lung Diseases, Obstructive / Q000453:epidemiology* / Q000503:physiopathology*; D008297:Male; D008800:Mexico / Q000453:epidemiology; D009589:Nitrogen Oxides / Q000009:adverse effects; D015995:Prevalence; D012621:Seasons; D013458:Sulfur Dioxide / Q000009:adverse effects; D014797:Vital Capacity / Q000502:physiology
chemical_list: D009589:Nitrogen Oxides; D013458:Sulfur Dioxide; D002248:Carbon Monoxide