Accurately measuring NH 3 produced from poultry litter and emitted from mechanically ventilated broiler houses continues to be a challenge. Many technologies and methods are available to measure NH 3 , with costs ranging from inexpensive (but rather inaccurate, such as colorimetric tubes) to expensive (for precision analytical equipment such as laser spectrometers). This study investigated the variability among selected low, midrange, and high-cost instruments. Inter-instrument and

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... ent comparisons were made using colorimetric pull tubes and dosimeter tubes, electrochemical sensors, and tunable-diode open-path laser spectrometers (OPL). This study consisted of inside and outside broiler house studies to evaluate instrument performance under different environmental conditions and NH 3 concentrations. The OPL showed the least variation during the in-house and outside comparisons. The electrochemical sensors and colorimetric tubes performed well at NH 3 levels typically found in a properly ventilated broiler house. With no ventilation, variation among instruments increased as NH 3 concentrations increased. With the exception of the OPL, concentrations on the outside were too low and environmental elements were too harsh for these instruments to perform well.