Occupational asthma is currently the most common lung disease in Western countries. It often occurs in people at the peak of work, and can affect everyone. There are few diseases that can cause so many problems so easily. An unjustified clinical diagnosis is also often met, as is his omission. The advice to leave work turns patients into unemployed and socially vulnerable people. Currently, there are reliable recommendations and approved treatment standards. This article is based on them. The definition of occupational asthma is very complex and a bit controversial. Asthma related to working conditions worsens with continued work and improves with departure from the workplace. If a worker already suffers from asthma and deterioration occurs at the first significant exposure to an irritating agent, then the mechanism is more likely to be allergic, and the disease is asthma, which progresses in the conditions of work. An example is asthmatics working in cold warehouses or in workrooms with a significant content of sulfur oxide. One intense exposure to the stimulus can lead to the development of asthma, which can persist for months or a lifetime without increased bronchial hyperreactivity. It is commonly referred to as acute, irritant (or toxic) asthma. After intense exposure to the stimulus, the worker needs to continue to work in conditions with a low content of irritant, as well as the worker already suffering from asthma. Changing jobs is usually not necessary. The most common cause of the disease is considered to be exposure to chlorine. Allergic occupational asthma is characterized by the presence of a latent period between the first contact with the stimulus under working conditions and the development of symptoms. Hypersensitivity occurs even at lower than previously concentrations of the irritating substance. The disease can occur for the first time or in people already suffering from asthma, when hypersensitivity to another substance develops. For example, a doctor with asthma may develop increased sensitivity to latex. In this case, individual intolerance to latex occurs, from which, for example, medical gloves are made. Allergic occupational asthma is divided into high molecular weight (in the presence of specific IgE) and low molecular weight (without IgE).