Tokyo-Yokohama asthma. A review and some current concepts.

Soon after the occupation of Japan, military physicians began recording an unusually large number of patients with asthma. Subsequent reports labeled the condition "Yokohama asthma" and called it a new environmental respiratory disease. It occurred in the Tokyo-Yokohama area, in previously healthy persons, from October to May during the time of the heaviest concentration of air pollution. The disease begins with cough at night, wheezing and shortness of breath, and apparently does not respond to the usual forms of treatment for asthma. It was reported that the symptoms subsided upon removal of the patient from the Tokyo-Yokohama area but abruptly recurred upon return to the area. It has been implied that the disease is a hypersensitivity phenomenon due to some unknown contaminant in the atmosphere. More recent studies indicate that Tokyo-Yokohama asthma is not a disease but a syndrome seen in people with bronchial infections and asthma. The high level of air pollution is thought to have an aggravating rather than a sensitizing effect.