and “hot tub lung” are common names for types of hypersensitivity pneumonitis that result from exposure to some types of thermophilic actinomyces, mycobacteria and molds. Avian proteins in bird feces and feathers Whole body or chest radiation therapy used for cancer treatment Symptoms Physical manifestations of Pneumonitis range from mild cold-like symptoms to respiratory failure. Most frequently, those with pneumonitis experience shortness of breath, and sometimes a dry cough. Symptoms usually appear a few hours after exposure and peak at approximately eighteen to twenty-four hours. Other symptoms may include: Malaise Fever Dyspnea Flushed and/or discolored skin Sweating Small and fast inhalations Without proper treatment, pneumonitis may become chronic pneumonitis, resulting in fibrosis of the lungs and its effects: Difficulty breathing Food aversion Lethargy End-stage fibrosis and respiratory failure eventually lead to death in cases without proper management of chronic pneumonitis. Diagnosis A chest X-ray or CT is necessary to differentiate between pneumonitis and pneumonia of an infectious etiology. Some degree of pulmonary fibrosis may be evident in a CT which is indicative of chronic pulmonary inflammatory processes. Diagnosis of Pneumonitis is often difficult as it depends on a high degree of clinical suspicion when evaluating a patient with a recent onset of a possible interstitial lung disease. In addition, interpreting pathologic and radiographic test results remains a challenge to clinicians. Pneumonitis is often difficult to recognize and discern from other interstitial lung diseases. Diagnostic procedures currently available include: Evaluation of patient history and possible exposure to a known causative agent High-Resolution Computed Tomography (HRCT) consistent with pneumonitis Bronchoalveolar lavage with lymphocytosis Lung biopsy consistent with pneumonitis histopathology Exposure to causative agents of pneumonitis in a specific environment can be confirmed through aero/microbiologic analysis to verify its presence. Subsequent testing of patient serum for evidence of serum specific IgG antibodies confirms patient exposure. Clinical tests include chest radiography or (HRCT) which may show centrilobular nodular and ground-glass opacities with air-trapping in the middle and upper lobes of the lungs. Fibrosis may also be evident. Bronchoalveolar Lavage (BAL) findings coinciding with pneumonitis typically include a lymphocytosis with a low CD4:CD8 ratio. Reticular or linear patterns may be observed in diagnostic imaging. Pneumonitis may cause subpleural honeycombing, changing the shape of the air spaces in an image, which may be used to identify the respiratory disease. The interlobular septa may also thicken and indicate pneumonitis when viewed on a scan. Histological samples of