Agricultural odors are a combination of many different gases in extremely low concentrations. The slightest difference in composition can alter the way a person perceives the odor. To distinguish among different odors, the concentration of gases must be measured. Determining the exact composition of an odor is very difficult, expensive, and time consuming. Two common approaches used to measure odors are explored in this publication. They are gas measurement (equipment) and odor measurement (people). Both have pros and cons.