Exposure to chemical substances can cause adverse effects on the respiratory system, which consists of the nasal passages, pharynx, trachea, bronchi, and lungs. Respiratory toxicity can include a variety of acute and chronic pulmonary conditions, including local irritation, bronchitis, pulmonary edema, emphysema, and cancer. It is well known that exposure to environmental and industrial chemicals can impair respiratory function. Ground-level ozone, the main component in smog, causes breathing problems, aggravates asthma, and increases the severity and incidence of respiratory infections.
Acute exposure to respiratory toxicants can trigger effects ranging from mild irritation to death by
asphyxiation. Prolonged exposure to respiratory toxicants can cause structural damage to the lungs,
resulting in chronic diseases such as pulmonary fibrosis, emphysema, and cancer. Pulmonary fibrosis is a serious lung disease in which airways become restricted or inflamed, leading to difficulty in breathing. It can be caused by exposure to coal dust, aluminum, beryllium, and carbides of
tungsten. Emphysema, a degenerative and potentially fatal disease, is characterized by the inability of the lungs to fully expand and contract. The most common cause of emphysema is heavy cigarette smoking, but the disease can also be induced by exposure to aluminum, cadmium oxide, ozone, and nitrogen oxides. In addition, several toxicants are known to cause respiratory cancer. Examples of well-established human lung carcinogens are cigarette smoke, asbestos, arsenic, and nickel.