The Hidden Killer

At NCH Life Sciences, our mission is to develop probiotic solutions that produce measurable improvements in digestive health. By striving to deliver healthier air and water, we help customers increase production efficiency while reducing environmental impact. Our commitment to our customers goes beyond our biological products, with product lines spanning from chlorine control, wastewater management and odor control.

Odor control is an integral part of biosecurity and plays a significant role in animal and human health. The three primary sources of odor on farms are animal housing, manure storage, and land application. Unmanaged odor on farms can lead to respiratory issues, headaches, irritation in the eyes and nose, drowsiness, and in some cases, death in both animals and humans. In addition, odor on farms can travel to surrounding residencies under specific wind patterns, which leads to fines on farms. These are the reasons why it’s essential to know the source of the odor.

Possible odor sources in animal housing

Wet Litter, Poor Ventilation, Manure, Poor Farm Management, Improper Bedding, Dust, Improper Monitoring, Spoiled or Moldy Feed, Carcasses, Poor infrastructure, Dirty water management

Possible odors produced by manure decomposition that will spread by land application if not properly monitored and distributed

Gas Odor Characteristic Exposure limits Effects
Ammonia (NH3) Sharp, pungent Lighter than air. Results from anaerobic and aerobic activity. 10 ppm   Irritation to eyes and nose. Asphyxiating at high levels.  
Hydrogen sulfide (H2S) Rotten egg smell Heavier than air. Low odor threshold. Soluble in water 10 ppm Toxic: causes headache, dizziness, nausea, unconsciousness, death.
Methane (CH4) Odorless Lighter than air. Product of anaerobic activity. 1,000 ppm   Headache, asphyxiant, explosive in 5-15% mixture of methane with air
Carbon dioxide Odorless Heavier than air   5,000 ppm Drowsiness, headache. It can be asphyxiating.
Volatile organic acids Strong High odor potential under anaerobic conditions. Low odor potential under aerobic conditions.    
Phenolic Strong P-cresol has a lower odor threshold than hydrogen sulfide. Present in raw manure and concentrations increase under anaerobic conditions.      

Source: The University of Missouri’s Department of Agricultural Engineering

Controlling each source of odor is crucial for farm productivity and for human and animal health. Contact NCH Life Sciences ( to learn about our odor control product line.