title: [Relationship between emergency consultations for respiratory diseases and air pollution in Juarez City, Chihuahua].
abstract: OBJECTIVE
  To assess the relationship of < or = 10 microns particles (PM10) and atmospheric ozone concentrations, with the daily number of emergency visits due to asthma and acute respiratory diseases, among children aged under 15, living in Ciudad Juarez, Chihuahua, Mexico.
  
  
  METHODS
  Between 1998 and 1999, an ecologic study was conducted. Atmospheric data were obtained from the Environmental Protection Agency (EPA), from eight monitoring stations located in Ciudad Juarez, Chihuahua, and EI Paso, Texas. From July 1997 to December 1998, data from emergency room visits for respiratory illness were abstracted from existing medical records of two Mexican Institute of Social Security (IMSS) hospitals in Ciudad Juarez. Diagnoses were classified into two groups: a) asthma, and b) upper respiratory infections (URI), according to the International Classification of Diseases (ICD-9 and/or IDC-10). Statistical analysis was carried out using the Poisson regression time series method.
  
  
  RESULTS
  During the study period, the mean 24-hour PM10 level was 34.46 micrograms/m3 (SD = 17.99) and the mean ozone level was 51.60 ppb (SD = 20.70). The model shows that an increase of 20 micrograms/m3 in the mean 24-hour exposure to PM10 was related to an increase of 4.97% (95% CI 0.97-9.13) in emergency visits for asthma, with a 5-day lag, as well as to an increase of 9% (95% CI 1.8-16.8) when a cumulative 5-day exposure was considered. URI increased 2.95% as a cause of emergency room visits, for each 20 micrograms/m3 increase in the mean 24-hour exposure to PM10. The impact of PM10 on emergency visits for asthma was greater on days with ozone ambient levels exceeded 49 ppb (median value).
  
  
  CONCLUSIONS
  A positive association was found between environmental PM10 and ozone concentrations and the daily number of emergency room visits due to asthma and acute respiratory diseases, even with levels lower than the Mexican standard levels. Also, a synergic effect between PM10 and O3 was found.
authors.affiliation: Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública, Morelos, México. lhcadena@insp3.insp.mx
authors.forename: L
authors.initials: L
authors.lastname: Hernández-Cadena
authors.forename: M M
authors.initials: MM
authors.lastname: Téllez-Rojo
authors.forename: L H
authors.initials: LH
authors.lastname: Sanín-Aguirre
authors.forename: M
authors.initials: M
authors.lastname: Lacasaña-Navarro
authors.forename: A
authors.initials: A
authors.lastname: Campos
authors.forename: I
authors.initials: I
authors.lastname: Romieu
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000397:Air Pollution; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D008800:Mexico; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D014504:Urban Health