Comprehensive health interviews of residents living in the vicinity of large scale swine production facilities to evaluate exposures to airborne ammonia (7664417), dust, and endotoxin were conducted. Eight swine production facilities in Iowa were investigated. The facilities were stratified by size and operation in to four categories: small (four buildings, about 2,000 pigs, deep manure pits and lagoons), medium (six buildings, about 3,000 pigs, slurry store and deep manure pits) and large confinement (eight buildings, about 4,000 pigs, deep manure pits, pull plug systems and manure lagoons), and conventional facility (52 sows, no lagoon). Air samples were collected on 37 millimeter glass fiber filters in three piece closed face cassettes at a flow rate of 2 liters per minute (l/min) using personal sampling pumps. Ammonia samples were collected in personal sampling pumps at a flow of 0.8l/min. Air sampling was conducted on 1 day at each site over a time period of 6 hours. One sample was taken inside the livestock facility and five samples were taken outside of each facility at a distance of 60 meters and height of 2 meters. In most cases the outdoor samples showed endotoxins and total dust levels to be below detectable limits. Indoor total dust concentrations ranged from 0.75 to 2.59mg/m3. Indoor endotoxin concentrations ranged from 58 to 526 endotoxin units (EU)/m3. Hydrogen-sulfide (7783064) was not detected at any sample location. Mean temperatures ranged from 72 to 89 degrees-F, with relative humidity being 44 to 85%. Outdoor ammonia concentrations ranged from 0.01 to 0.46 parts per million (ppm). Indoor ammonia concentrations ranged from 1.27 to 2.59ppm. Concentrations of ammonia were always greater downwind of sources. No correlation was noted between ammonia, dust or endotoxin and temperature and relative humidity. The authors conclude that better methods for evaluating airborne concentrations of sulfides, mercaptans, and other manure generated gases in the vicinity of swine production facilities are warranted.