Keeping the ammonia levels low in your hog buildings is important to protecting the safety of your pigs and your workers.

An ammonia level of 10 parts per million is considered an excellent long-term goal, while 25 ppm is recommended as the daily time-weighted exposure level. The short-term ammonia-exposure standard from the Occupational Safety and Health Administration is 35 ppm.

Here are the average ammonia concentrations from various manure management practices.

Manure Management Systems                  Average Ammonia Concentrations
Manually Scraped Gutters                              25.0 ppm
Pit-Recharge                                                        4.6 ppm
Mechanical Scraper                                          16.4 ppm
Flush Under Flooring (fresh water)                 6.7 ppm
Flush Under Flooring (recycled water)            8.5 ppm
Deep Pits Under Buildings                                7.5 ppm
Source: Joe Zulovich, University of Missouri animal structures specialist

Joe Zulovich, University of Missouri animal structures specialist, says deep-pit systems have long-term averages below 10 ppm, but have had ammonia levels of 50 ppm or higher for several hours or days. The OSHA short-term industrial-worker exposure limit for ammonia is 35 ppm average over a duration of 15 minutes.

This means a worker entering a deep-pit building should spend only 15 minutes in the building for the entire day to stay within the industrial-worker standard for ammonia. Even though deep-pit buildings seem to have a reasonable average ammonia level, the buildings are not recommended because of the ammonia level variability and the hazard from hydrogen sulfide, says Zulovich.