Concentrated animal feeding operations (CAFOs) are being examined in several regions of the U.S. as major sources of ammonia and particulate matter precursors. The National Risk Management Research Laboratory (NRMRL) has previously measured ammonia concentrations around and estimated emissions from a swine production facility. In this paper we present the results from two new studies at swine finishing facilities. New data are collected for tunnel-ventilated pull-plug swine finishing barns using chemiluminescent ammonia measurements from the exhaust fans. Open-path Fourier transform infrared (OP-FTIR) measurements of a naturally ventilated pit recharge barn and its lagoon are used to develop emission factors in the second study. The data suggest that the barns are a significant source of ammonia, and that the current emission factors are not markedly different from these new data.