Strong acid solutions have been widely used in acid traps to determine concentrations of ammonia in ambient air or exhaust air stream. A study was carried out to examine factors that might affect the efficiency of sulfuric acid traps. An inverse relationship between the efficiency of the acid traps and the amount of ammonia to be trapped was observed. For the same volume of acid, the efficiency of the acid trap increased with the acid depth but overall, the efficiency at any given acid depth decreased as the amount of ammonia through the trap increased. The efficiency of the acid traps decreased at similar rates as the concentration of ammonia in the sample air increased but the efficiency of the trap was significantly higher at the lower airflow rate. Multi-point calibrations within the entire range of target measurements is recommended to provide accurate corrections of the measurements. This is an abstract of a paper presented at the 102nd AWMA Annual Conference (Detroit, MI 6/16-19/2009).