Is more appropriately referred to as hypersensitivity pneumonitis. Hypersensitivity pneumonitis is an inflammation of the lungs due to breathing in a foreign substance, usually certain types of dust, fungus, or molds. It has also called humidifier lung, extrinsic allergic alveolitis, farmer's lung, mushroom picker's disease, and bird breeder's lung. The condition is usually found in those whose home or work place contains high levels of contaminants. For example, as a result of fungus present in humidifiers, heating systems, and air conditioners found in homes and offices. Exposure to certain bird droppings (for example, among bird owners) can also lead to hypersensitivity pneumonitis. In farmers with repeated or intense exposure to dust from moldy hay, straw, and grain can lead to lung inflammation and acute lung disease. Over time, this acute condition may turn into long-lasting (chronic) lung disease. Symptoms of acute hypersensitivity pneumonitis may occur 4 - 6 hours after leaving the area and include: chills, cough, fever, malaise, or shortness of breath. Symptoms of chronic hypersensitivity pneumonitis may include, breathlessness especially with exertion, cough, often dry, loss of appetite, and unintentional weight loss. >p>Prevention is by avoiding material that causes lung inflammation.