Particulate matter (PM) associated with animal feeding operations is a concern for the occupants and the surrounding community. Baseline measurements of PM concentration and emission rate are the first step toward assessing the magnitude of concentrations and emissions and evaluating effectiveness of dust control strategies. This study presents the results of PM measurements at a high-rise layer house (approx. 250,000 hens) in central Iowa using tapered element oscillating microbalance (TEOM) equipment. Daily average concentrations of PM10 and PM2.5 over a 17-month measurement period were 393 (±257 SD) and 44 (±36 SD) µg m-3, respectively. Daily average PM10 and PM2.5 emission rates during the same monitoring period were, respectively, 26.1 (±15.8 SD) and 3.6 (± 3.7 SD) mg bird-1 d-1, or 8.16 (±4.94) and 1.13 (±1.16) g AU-1 d-1 (AU = animal unit = 500 kg body weight). PM emission rate was positively related to ventilation rate but was negatively related to relative humidity.