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RIDDING THE BARN OF AMMONIA
By Nancy S. Loving, DVM
No doubt you have entered a barn and been assaulted by the noxious fumes of ammonia. Some feel immediate effects
such as watering eyes and nose, and throat clos- ing. Then, there are the horses stabled in such an enclosed space with poor ventilation – where can they go to breathe sweet, fresh air?
The good news is that ammonia buildup in a barn is preventable to a large degree through sound management practices.
AMMONIA’S IMPACT
Ammonia is a severe respiratory tract irritant, especially of a horse’s upper airways. The EPA recommends that people should not be chronically exposed to more than 1.4 ppm (parts per million). Levels of 24 ppm create severe throat and nose irritation. However, at higher concentrations greater than 500 ppm, ammonia causes lower airway inflammation and pulmonary edema with potentially fatal consequences.
Studies confirm that stalled horses show more signs of upper and lower respiratory inflammation than pastured horses. Inflammatory conditions of the airways elicited by ammonia result in increased mucus, adverse effects on the immune response, and interference with the action of cilia lining the airways – these cilia serve as a natural defense to prevent dust and debris from entering into deeper parts of the respiratory tract. Ammonia’s negative impact detracts from a horse’s performance and vitality, particularly when the airways
are also assaulted by environmental dust, endotoxin, and other particulates.
CHECKING FOR AMMONIA
If you can smell ammonia in the stable, then it’s already above the recommended threshold for good air quality. Ammonia should be maintained below 10 ppm. Some people are extremely sensitive to very low levels, but most human recognition of ammonia smell doesn’t occur until 20 to 30 ppm, which is higher than desirable for horse health.
Ammonia is lighter than air, but the
highest levels exist near its source – urine and feces deposited in the stalls. This correlates
to the area within a horse’s breathing zone.
A useful test is to sit on a lawn chair in your horse’s stall with the stall door shut, and then read or just hang out. Your head is now at a horse’s breathing zone, so you experience air movement and quality comparable to what your confined horse breathes. The only thing missing is a 1,000-pound animal’s body heat and movements lofting dust from the bedding and hay and fumes from soiled bedding.
Many companies make relatively simple devices to measure ammonia. Some get a ‘snapshot’ of ammonia levels at given times while others provide a read-out over a longer period to chart a more accurate assessment of the horse’s exposure levels.
VETERINARY VIEWS
“If you can smell ammonia in the stable, then it’s already above the recommended threshold for good air quality.”
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