What's in the Air.

One word usually comes to mind when most people think of hogs--smell. From the grain they eat to the waste they produce, there's no question that hogs emanate an odor. Hog feed, typically a mixture of corn, soy beans, various grains and vitamins, produces dust that carries an odor and some particulate matter into the air. The breakdown of hog waste produces ammonia, hydrogen sulfide and other organic compounds, including particulates and methane. Typically, hog waste is flushed from the hog houses into open-air pits called lagoons, containing chemicals to process the manure compounds aerobically (using oxygen). When the lagoons are properly designed, sited, constructed and maintained, the lagoons can effectively treat hog waste (Williams, NCSU, Oct. 2000). However, if the lagoons (usually composed of clay or concrete) crack or are mismanaged or uncovered, the elements can become pollutants, emanating an almost-intolerable sulfur odor. With an open lagoon, ammonia gases rise into the air, falling back to the earth as "ammonia rain," contaminating streams and wells.

Since 1996, regulations controlling animal waste have become stricter, attempting to promote more tolerant relationships between hog owners and their neighbors. In addition, the NC Division of Air Quality and NC State University are jointly researching the role of animal operations in contributing nitrogen compounds to the air and the effects these compounds could have on streams and coastal waters. In fact, when hog waste is properly disposed of and lagoons and feed are completely covered, the odor is negligible. While there are several odor-controlling plans that have a minimal expense, such as covering feed and lagoons, waiting for a day when the air is still to pump a lagoon for spraying, fans that keep dust from entering ventillating systems, etc., chemical treatment and disposal of hog waste is very expensive for farmers.

Although there is no data that definitively indicates that hog waste adversely affects the physical health of the general population, the individual compounds of hog waste--ammonia and methane--can aggravate existing upper respiratory conditions and can cause adverse effects in others who breathe them on a daily basis. Ammonia, with its offensive odor, can irritate nasal and respiratory passages, particularly for sensitive people. Odor from hog farms affects individual people differently, depending on their tolerance level. Typically residents who live next to hog farms complain of more physical ailments than those who live further away. Some residents are immune to the odor. Others complain of tension, nausea and headaches from constant odor.

When the waste is effectively managed, environmental impacts and odor are minimal. However, when lagoons are cracked or uncovered, or it is not operating properly, the ammonia and methane can increase in intensity. One spokesperson from the NC Department of Agriculture said, "Hog farms will always have some odor, but it shouldn't be every day."

next>>