title: Experimental human exposure to inhaled grain dust and ammonia: towards a model of concentrated animal feeding operations.
abstract: BACKGROUND
  Ammonia and endotoxin-rich dust are present in high concentrations in swine confinement facilities; exposure to this environment is linked to workers' respiratory problems. We hypothesized that experimental exposure to ammonia and dust would impair pulmonary function, and that these exposures would be synergistic.
  
  
  METHODS
  We exposed six normal subjects and eight subjects with mild asthma to ammonia (16-25 ppm) and/or endotoxin-rich grain dust (4 mg/m3). Pulmonary function and exhaled NOx were measured before and after exposure.
  
  
  RESULTS
  There was no significant change in pulmonary function in the normal subjects following any of the exposure conditions. Among asthmatics, a significant transient decrease in FEV1 was induced by grain dust, but was not altered by ammonia; increased bronchial hyperreactivity was also noted in this group.
  
  
  CONCLUSIONS
  In a vulnerable population, exposure to grain dust results in transient airflow obstruction. Short-term exposure to ammonia does not increase this response.
authors.affiliation: Division of Pulmonary, Critical Care, and Occupational Medicine, Roy J. and Lucille A Carver College of Medicine, University of Iowa, Iowa City 52242, USA.
authors.forename: Sigurdur T
authors.initials: ST
authors.lastname: Sigurdarson
authors.forename: Patrick T
authors.initials: PT
authors.lastname: O'Shaughnessy
authors.forename: Janet A
authors.initials: JA
authors.lastname: Watt
authors.forename: Joel N
authors.initials: JN
authors.lastname: Kline
mesh_terms: D000328:Adult; D000641:Ammonia / Q000506:poisoning*; D000822:Animal Husbandry; D000818:Animals; D001249:Asthma / Q000503:physiopathology; D004391:Dust; D002523:Edible Grain / Q000506:poisoning*; D005260:Female; D006801:Humans; D019570:Inhalation Exposure; D008168:Lung / Q000502:physiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000209:etiology / Q000503:physiopathology; D016273:Occupational Exposure / Q000032:analysis / Q000517:prevention & control; D012129:Respiratory Function Tests; D013997:Time Factors
chemical_list: D004391:Dust; D000641:Ammonia