Millions of people suffer from allergies caused by everyday exposures to agents such as dust mites, cat dander, and pollens. Agents encountered by workers can also cause allergic problems such as asthma, nasal and sinus allergies, hives, and even severe anaphylactic reactions. Examples of these work-related agents include animal proteins, enzymes, flour, natural rubber latex, and certain reactive chemicals. Asthma is one of the more serious problems that can be caused by work-related allergy. It can cause recurrent attacks of symptoms such as wheezing, chest tightness, shortness of breath, and coughing. In severe cases, these symptoms can be disabling. Fortunately, when potential hazards are recognized, work-related allergies and asthma can often be prevented or their effects minimized.