Results of studies of airborne endotoxin concentrations in occupational environments were summarized. Airborne dust and bulk samples were collected during silage unloading, bedding production, cotton textile and nontextile operations, animal confinement and processing, grain storage, peanut shelling, and mushroom growing and in biotechnology laboratories in the United States and in rice production and cotton textile mills in the Peoples Republic of China. These were analyzed for endotoxins using the amebocyte lysate assay. Selected data were tabulated. The endotoxin concentrations in bulk oats and an oat, soybean, and cotton mixture in a grain storage bin in Alabama averaged 122.66 and 173.87 endotoxin units per milligram (EU/mg), respectively. The endotoxin concentrations in a corn silage silo in New York ranged from 104.07 to 1.09EU/kg. The endotoxin content of a snow inducer found in a biotechnology laboratory in California averaged 50304.84EU/mg. Endotoxin concentrations at a mushroom farm in Florida ranged from 1.12EU/mg to 611.28EU/mg. Airborne endotoxin concentrations in a hay silage silo in New York averaged 463.70EU/mg for respirable dust and 872.70EU/mg for total dust. Airborne endotoxin concentrations in the exhaust dust of a peanut shelling operation were 226.10 and 251.80EU/mg for particle sizes greater than 10 millimeters (mm) and less than 10mm, respectively. The author concludes that endotoxins are ubiquitous pollutants and present a potential risk of respiratory impairment for agricultural workers exposed to endotoxin containing dust.