Experimental human exposure to inhaled grain dust and ammonia: towards a model of concentrated animal feeding operations

Am J Ind Med. 2004 Oct;46(4):345-8. doi: 10.1002/ajim.20055.


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.

Conclusion: In a vulnerable population, exposure to grain dust results in transient airflow obstruction. Short-term exposure to ammonia does not increase this response.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Ammonia / poisoning*
  • Animal Husbandry
  • Animals
  • Asthma / physiopathology
  • Dust*
  • Edible Grain / poisoning*
  • Female
  • Humans
  • Inhalation Exposure
  • Lung / physiology
  • Lung / physiopathology
  • Male
  • Middle Aged
  • Occupational Diseases / etiology
  • Occupational Diseases / physiopathology
  • Occupational Exposure / analysis
  • Occupational Exposure / prevention & control
  • Respiratory Function Tests
  • Time Factors


  • Dust
  • Ammonia