Olfactometry Lab

FAQ:

Why Olfactometry?
As neighborhoods and agriculture grow, their boundaries often become adjacent to each other.  Odor is one of the most often cited nuisances in livestock production.  Olfactometry is the study of the measurements of odors.  The use of olfactometry in odor management for all sorts of livestock production systems (as well as manure storage and application) is an effective starting point for beginning or monitoring odor mitigation techniques. 

How much does odor analysis cost?
Fees for odor evaluation are contingent upon the number of samples analyzed for a particular project and if ammonia/hydrogen sulfide measurements are taken.  Typically samples are $85-$90 each.  Please call the lab manager for assistance.

How are odor samples collected?
Samples are collected in Tedlar® bags.  A vacuum chamber is generally the best way to obtain the sample.  Samples must be evaluated within 24 hours of collection. 

How does an odor panel work?
The odor panel consists of four trained panelists in the morning and four different panelists in the afternoon.  (Each sample must be sniffed by eight different people.  Since this lab employs mostly students, we split up the evaluation session to accommodate student schedules.)  The panel is four hours in duration, two in the morning and two in the afternoon.  The samples are evaluated one at a time, with panelists called into the olfactometer room one at a time.  There are up to eight samples evaluated in a two-hour period.

What does an odor Panelist do?
The odor Panelist evaluates odor samples for a number of qualities.  Most of the time in the ISU lab, odor Detection Threshold is the quality that is evaluated.  Before each panelist assesses the odor, the Panel Leader has the responsibility to choose a dilution level where it is assumed that the assessor will not detect the odor.  The concentration is increased (doubled) between dilution levels until the assessor becomes aware of the odor.  The assessor indicates by pressing a button whether they are guessing which presentation (there are three at each dilution level) has the odor, or if they detect the odor. 

What is n-Butanol?
n-Butanol is the standard gas used in olfactometry.  This means that other odor Detection Thresholds are compared against that of the n-Butanol.  Each Panelist is required to maintain a certain sensitivity to the gas.  The value of 20-80 parts per billion is representative of a “normal” sense of smell.