1343 1 Presented at a symposium titled “The Biology of Livestock Odor” at the ASAS/ADSA Midwestern Mtg., March 18, 1997, Des Moines, IA. Received May 21, 1997. Accepted December 18, 1997. Livestock Odors: Implications for Human Health and Well-Being 1 Susan S. Schiffman Duke University Medical School, Durham, NC 27710 ABSTRACT: The purpose of this paper is to examine the potential effects of livestock odors on the health and well-being of neighbors. Complaints of odor nuisance have become more frequent in communities surrounding areas with high concentrations of livestock. This increase in complaints from livestock odors parallels increased complaints of odor in general, including ammonia, diesel exhaust, beauty products, cleaners, and paints. Persons who report symptoms from odors generally find problems with many different types of odorous compounds. A review of recent studies suggests that the main complaints of health symptoms from odors are eye, nose, and throat irritation, headache, and drowsiness. Sensory irrita- tion (pungency) can be produced by a broad range of odorous volatile organic compounds from trees, flow- ers, foods (pepper and ginger) as well as emissions from livestock operations. Odors can also potentially affect mood and memory. Further research is required to assess fully the health impact of odors in order to establish recommendations for air quality guidelines based on scientific data. Key Words: Odors, Senses, Health, Livestock, Pigs 1998 American Society of Animal Science. All rights reserved. J. Anim. Sci. 1998. 76:1343–1355 Introduction The purpose of this paper is to examine whether odorous compounds from agricultural operations could potentially alter health status in humans. With the move on a nationwide scale to greater concentrations of livestock in confined areas, complaints of odor nuisance by surrounding communities have become more frequent (Bundy, 1992). Smell sensations are induced by inhalation of volatile organic compounds ( VOC) . There are four main ways that odors could potentially affect human health. First, the VOC themselves could produce toxicological effects. Shusterman (1992), however, suggested that any health symptoms from odors are probably caused by nontoxicological mechanisms. Second, odorant com- pounds could cause sensory irritation in the eye, nose, and throat. Third, the VOC could stimulate sensory nerves to cause neurochemical changes that poten- tially influence health. Fourth, health effects from agricultural odors could be due to cognitive and emotional factors such as stored mental experience with similar odors or attitudes toward unpleasant odors. Complaints of health effects from odors as- sociated with livestock operations probably derive from a combination of physiological and psychogenic sources. Human and animal studies suggest that expression of health symptoms involves a complex interplay between biological and behavioral/psychoso- cial influences (Engel, 1977; Schwartz, 1982; Kaplan, 1990; Baltrusch et al., 1991; Friedman et al., 1995). Discussion: Potential Effects of Odors on Health and Well-Being The experimental data on the effect of unpleasant odors on human health will be addressed in this paper in a question-and-answer format. Each question will examine whether unpleasant odors from livestock operations could have a negative impact on physical or mental health status. Question 1: What Health Symptoms Do Persons Exposed to Odors Complain About? A review of recent studies suggests that the main complaints of health symptoms from odors are eye, nose, and throat irritation, headache, and drowsiness. Persons who report symptoms from odors generally find problems with a broad array of compounds. Thus, any scientific studies of putative effects of odors from livestock operations must also examine other odors in the rural environment that do not arise from livestock operations. Hudnell et al. (1992) at the Environmental Protec- tion Agency (EPA) studied health symptoms in 66