The clinical characteristics of 22 cases of toxic pulmonary edema treated at Shenyang Research Institute, Industrial Hygiene and Occupational Diseases, Shenyang, Peoples Republic of China from 1970 to 1987 were described. The cases consisted of ten persons exposed to high concentrations of nitrogen-dioxide (10102440), six exposed to chlorine (7782505), two exposed to sulfuric-acid (7664939) fumes, one exposed to ammonia (7664417), two exposed to dimethyl-sulfate (77781), and one who was overexposed to phosgene (75445). All cases resulted from accidental exposure and resulted in symptoms such as breathlessness, coughing, a feeling of pressure on the chest, cyanosis, foamy sputum, and dry and crepitant rales. The symptoms developed 30 minutes to 72 hours after exposure, mean 4.3 hours. The shortest latency period was observed for persons exposed to chlorine and the longest for the person exposed to phosgene. Chest X-rays of the subjects contained shadows. The symptoms generally abated before the shadows disappeared, mean resolution times 13.7 and 27.8 days. Twenty one cases recovered without any pulmonary sequelae after treatment. The most severe cases of pulmonary edema occurred in which corticosteroid treatment was delayed. The person poisoned by phosgene died. Prompt corticosteroid treatment resulted in faster clearing of the chest X-rays than delayed corticosteroid treatment, mean 7.4 versus 30 days. The authors conclude that prompt treatment with corticosteroids is the best treatment for acute irritant gas poisoning.