Air Quality - Odor

What are odors called and how are they measured?

An odorant is a specific gas, such as ammonia or hydrogen sulfide, which can contribute to the creation of odors perceived by humans.

Odors are complex mixtures of odorants, of which over 160 different types have been identified in swine manure alone. An odorant is not considered an odor until it is perceived by humans.

Olfactometry is the use of the human sense of smell to characterize odors. The human nose can detect over 10,000 different odors.

What are some of the challenges with managing odors?

Individual gas concentrations are not necessarily correlated with “odor”. Nuisance odors are often transient and difficult to measure objectively. To establish objective thresholds, very strict protocol is needed to conduct the measurements.

What is Pennsylvania’s Odor Management Program?

The Commonwealth’s Odor Management Program is a planning approach that addresses the potential impacts of odors, and then implements management strategies or technologies to minimize impacts. Pennsylvania’s program was authorized under Act 38 of 2005. An odor management plan is site-specific and assesses potential odor impacts in order to identify the best possible, implementable odor management practices

The plan does not require the elimination of odors, rather proactive management of them. Odor management plans are required for concentrated animal operations and concentrated animal feeding operations for new construction activities of animal housing or manure storage. The program does not include land application of manure or existing facilities.