Airborne dust particulates and gases, such as ammonia, hydrogen sulfide and carbon monoxide, are almost always present in confinement hog operations.
In addition, hundreds of other gases can also be found in trace quantities. While some of these gases can be hazardous only at high concentrations, there is some concern that long-term exposure to lower levels of dust and some gases could cause health problems for barn workers.
“Gases, like ammonia, when present in typical swine barns, are normally found at levels where you won't expect adverse effects,” explains Bernardo Predicala, a research scientist with the Prairie Swine Centre in Saskatoon, Saskatchewan. “While typical gas levels are not considered harmful, a full evaluation of the long-term health effects for the people who are actually working in the barn is needed.”
Besides gases, there are all kinds of airborne particulates made up of feed and small amounts of animal fecal matter, as well as fibers from bedding or construction materials. Gases can also be absorbed by dust and inhaled by workers. The limits of exposure to airborne particulates relevant to barn environments have not yet been established, Predicala says.
Technology exists to clean up all kinds of undesirable gases from the workplace. However, installation costs remain a concern.
“It is hard to put a cost-benefit figure on intangibles like improved air quality,” admits Predicala. “One way is to predict some kind of financial benefit to the entire operation, say fewer (worker) sick days. Further work needs to be done to establish a direct link between improved air quality and increased number of productive days on the job, and consequently, to reduced medical costs per worker.”
Lower Recruitment Costs
Worker recruitment and retention is another reason to improve air quality. In the past, barn workers with farming backgrounds were likely to be more tolerant of a barn working environment. Today, with an increasing percentage of hired labor from varying backgrounds, workers are becoming more aware of existing occupational regulations. They are more likely to insist on improved working conditions, especially for air quality.
Barn owners are faced with the difficult choice of installing systems to improve air quality or lose good workers. Both are expensive.
“This is why our main focus is to continue to develop cost-effective technologies that will work in the hog industry,” Predicala says. Air quality in barns can be improved by as much as 90% using simple techniques.
Improving Air Quality
“We employ three main approaches to improving air quality in swine barns,” Predicala says.
- Eliminate the contaminant source
“We've manipulated the diet to remove the nitrogenous compounds from which ammonia is generated,” he explains. “In one experiment, feeding pigs a low-protein with fermentable carbohydrate diet reduced their production of ammonia by 42% of that produced by a standard diet.”
- Eliminate what's been released to the air
Researchers found that sprinkling a small quantity of canola oil on a regular basis reduced airborne dust and particulates by 90%. Other readily available vegetable oils also work.
- Eliminate what is coming out of the building
“Biofilters — using straw, for example — clear out contaminants from exhaust air,” Predicala says.
New Methods Investigated
Predicala is also looking into new methods of managing hydrogen sulfide (H2S) in the barn. This potentially hazardous gas forms by the anaerobic decomposition of manure. As long as manure remains undisturbed, it is quite stable and remains in suspension.
Workers are at risk of being exposed to spikes in H2S levels when pit plugs are pulled to clear manure from a room. Predicala's team has developed a remote-operated plug-pulling system that allows manure removal without workers entering the room, thus eliminating worker exposure.
Another simple way to drastically lower H2S levels is to drain manure pits daily and use a scraper system to ensure the pit is completely cleaned. “H2S levels are generally minimal when the manure is not stored for long durations,” Predicala says. “The scraper system proved very effective as a method of H2S control, reducing H2S levels by an average of 90%.”
Currently, Predicala is experimenting with installing water sprinklers under the slats, above the manure pit. Theoretically, because H2S is water soluble, if agitated pits are sprayed with water, H2S can be put back into solution quickly and reduce health hazards. To date, the results are promising.