TRC Logo

1Source Safety and Health is now part of TRC, a leading national provider of engineering and consulting solutions supporting a clean energy future. Learn more.

Related Links

Read our latest Risk Factor Newsletter:

3/29/2021 - Odor Surveys and Assessments - 2021

If you ever had an odor or indoor air quality issue within your facility you can appreciate the difficultly in identifying the sources or causes and responding to questions from employees.

What Smells?

Friday, July 24, 2009
What Smells?

Whenever an unfamiliar odor is perceived within a building, it conjures up a level of concern that the air quality is poor and the air is unhealthy. Odors do not equal unhealthy air. This is rarely the case. Unfortunately, if just one employee believes it, you now have a problem. Legitimate or not, it has to be addressed. If you have ever had an odor issue within your facility, you will know how difficult it is to identify a source and a cause.

This is especially true when the odors are intermittent, or move around from area to area within the building. Please remember that finding the source of an odor and resolving the problem require a well-planned approach and time for implementation.

HINT: Do not do air sampling to identify compounds. Why? Typically, odor-causing compounds have very low odor thresholds and will not be detected by analytical equipment. In other words, in many cases your nose can detect the presence of compounds before sampling can! Some instruments may be used later in the investigation.

What Smells?There are several steps to resolving odor issues. The first is to meet with employees and develop a list of trends and possible sources. With this information, an Odor Event Log is developed for employees to log in characteristics of the odor over several weeks. Input from employees is critical not only because it may be accurate, but also because the process empowers the employees to be part of the solution. Second, review the input from the employees along with the Odor Event Log to identify any possible trends related to day of week, time of day, weather conditions (wind, sun, clouds, humidity, rain, etc) processes in the building, etc. Looking for trends is important, as the release of an odor from an indoor source is generally regulated by a change in its pathway and driving forces. If you cannot identify any trends, review the information with several people including the employees who are affected. At this point you might choose to retain a consultant with significant experience in odor investigation to assist.

What Smells?Third, based on the characteristics of the odor episodes, you should now begin to investigate building systems that could be contributing to the problem. For example, if the odor is sweet or aromatic you might want to look at possible entrainment from outdoors, or for moisture sources under impervious flooring (ceramic, vinyl, etc.), as trapped moisture allows for the growth of bacteria that can release organic compounds.

HINT: Remember to look under and behind walls, flooring and ceilings. You might need to do some destructive removal of materials in order to get to possible sources. Remember, it is as important to rule out sources as it is to find the actual source.

Although most of an odor investigation can be accomplished by looking and smelling, there typically will be a need for instrumentation to measure pressure differentials or to measure certain gases like methane or organic compounds to track down an exact emission point.

HINT: For more information, visit our website at and go to the Odor web page under Indoor Air Quality Management. There you will find additional information.

Please contact Harry M. Neill, CIH, Vice President, at 610.524.5525, ext 15, or email to discuss any questions or to request a proposal.