This on-going study is continuously monitoring emissions of gases including ammonia, hydrogen sulfide, carbon dioxide, methane and (intermittently) selected odorous volatile organic compounds (VOCs) as well as particulate matter (PM) from a 2500-head sow farm consisting of two gestation barns and one farrowing barn in central Iowa. An on-farm instrumentation shelter houses the equipment for measuring pollutant concentrations at representative barn air inlets and outlets, barn airflows, operational processes and environmental variables. Sampling began in July 2007 with data logged every 15 s and 60 s; sampling will continue for 24 months in total. Data are retrieved with network-connected PC, formatted, and validated for calculations of emission rates. A multipoint air sampling system draws air sequentially from representative locations at the barns and delivers it to a manifold from which on-line gas analyzers draw their subsamples. Different size PM including total suspended particulate (TSP), PM10 and PM2.5 are measured in real time using tapered element oscillating microbalances (TEOMs) and a Beta Gage PM analyzer. Mechanically-ventilated barn airflows are estimated by continuously measuring fan operational status and building static pressure, in combination with calibrated curves for each fan’s airflow. Specific processes that directly or indirectly influence barn emissions, including pig activity, manure management/handling and feeding, are measured. Environmental parameters including inside and outside air temperatures and humidity, wind speed and direction, and solar radiation are also monitored. Feed and water consumption, manure production and removal, swine mortalities, and animal production are recorded. Samples of feed, water, and manure are collected and analyzed for total nitrogen and total sulfur.