Do H2S monitors belong on the swine farm?: Part one

Should Hydrogen Sulfide (H2S) monitors be worn on swine production sites during manure transfer?

We lost 200 head of finishing pigs to hydrogen sulfide poisoning during routine manure pumping. We were walking back from lunch with assignment to scrape pens and fortunately, our father recognized the ominous silence as we neared the finishing barn. Had he not been with us, 3 of his children would have walked into the same fate as those pigs." By using the appropriate monitoring safety equipment and guidelines during agitation, potentially fatal situations can be avoided.

Hydrogen sulfide is a toxic colorless, flammable gas a by-product of anaerobic bacterial reduction of sulfates. Any time manure is being agitated or when shallow-pit plugs are pulled there is a potential for airborne concentrations of H2S to become elevated, potentially putting both workers and pigs at risk of being overexposed

The H2S concentration considered immediately dangerous to life and health (IDLH) is 100 ppm. Above 600 ppm, a person can die after only one or two breaths. It is important for farms to identify situations and practices where there may be increased amounts of airborne H2S.  Field studies have shown that H2S concentrations can exceed this level quickly during slurry agitation with concentrations recorded as high as 1,300 ppm

Human detection and awareness:

Human exposure to hydrogen sulfide is primarily through inhalation. The “rotten egg” smell can be detected at low levels, but with continuous low level exposure or at higher concentrations the ability to smell the gas - even though it is still present - is lost. The ability to smell H2S may begin to dull at 50 ppm. You cannot depend on your sense of smell for indicating the continuing presence of H2S or for warning of hazardous concentrations

MIOSHA’s (Michigan Occupational Safety and Health) Occupational Health Standard Part 700 – Agriculture specifies that an employee’s average eight-hour airborne exposure cannot exceed 10 ppm or 1 mg/m3. A hog farmer in Michigan is required to follow MIOSHA health and safety standard requirements.

H2S awareness training on swine farms in Canada has proven effective in changing attitudes regarding safety of employers and employees. Hydrogen sulfide monitors are being used when liquid manure is being agitated or when pits plugs are pulled within barns systems.  

Training for H2S covers properties of H2S, exposure limits, detection, and the importance of standard operating procedures and emergency response plans. Pork producers should be quick to appreciate the importance of H2S monitors. First, they provide early detection of the gas within a facility. This knowledge, when coupled with employee training, helps people understand when to immediately exit that facility.

The monitor can also be used to determine if, after turning on the ventilation, the H2S level is lowered and it is safe to enter.  Individual monitors can be purchased for a reasonable cost of $130 or up to $1,000 depending on battery life and sensory levels.  

In part two of this Michigan State University Extension series there will be tips on how to deal with rescue and recovery of someone over exposed to H2S.


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