Allergic alveolitis, also known as exogenous allergic alveolitis, is a type III or IV allergic reaction triggered by stimulation of the body by foreign antigens. After the body is exposed to allergenic substances such as pollen and dust, the immune response is activated in the alveoli, which is mainly mediated by cellular and humoral immunity, leading to an inflammatory reaction in the alveoli in the small airways, which can lead to pulmonary fibrosis in the chronic stage. Once allergic alveolitis is formed, the organism will have elevated body temperature, chills, dyspnea and even difficulty in breathing, etc. The examination of this lesion mainly relies on bronchoalveolar lavage, and its detected cells are mainly elevated CD8+ T lymphocytes. If contact with dust and other things appear fever, affecting breathing should immediately seek medical attention.