Yokkaichi Asthma


Yokkaichi asthma was a major health crisis that occurred in the city of Yokkaichi in Mie Prefecture, Japan, between 1960 and 1972. Known as one of the “Four Big Pollution Diseases of Japan,” it was caused by the burning of crude oil and from petrochemical processing facilities and refineries, which released huge amounts of sulfur oxide and other pollutants into the atmosphere. Such pollution caused serious smog, which resulted in numerous respiratory-related problems to many local residents.


Nowhere is the connection between industrial development and environmental and human health deterioration more graphically demonstrated than at Yokkaichi, Japan. An international port located on the Ise Bay, Yokkaichi was a major textile center by 1897. The shipping business shifted to nearby Nagoya in 1907, and Yokkaichi filled in its coastal lowlands in a successful bid to attract modern industries, especially chemical processing, steel production, and oil and gasoline refining.

Spurred by both the World War II (1939–1945) demand and the postwar recovery effort, several more petrochemical companies were added through the 1950s, creating an oil refinery complex called the Yokkaichi Kombinato. In 1959 it began 24-hour operations, and the sparkle of hundreds of electric lights became known as the “million-dollar night view.” Although citizens took pride in the growing industrial complex, their enthusiasm waned when air pollution and noise pollution created human health problems. As early as 1953, the central government sent a research group to try to discover the cause, but no action was taken. Instead, the petrochemical complex was expanded.


The construction of the Daichi Petrochemical Complex was begun in 1955 as a way for Japan to start converting from coal to petroleum as its primary source of fossil fuel. The city of Yokkaichi was selected as the site of the new complex. A second petrochemical production complex was constructed north of Yokkaichi in 1960 in order to increase capacity for petrochemicals. For even larger capacity, a third complex became operational in 1972.

Causes and symptoms

In the early 1960s, residents of Yokkaichi began to complain of respiratory problems. For instance, increased incidence of chronic obstructive pulmonary disease (COPD) and bronchial asthma were especially noticeable at this time. The cause of the disease was air pollution from sulfur oxide. It became known as Yokkaichi asthma (Yokkaichi Zensoku, in Japanese). As citizens began to complain about breathing difficulties, scientists documented a high correlation between airborne sulfur dioxide concentrations and bronchial asthma in schoolchildren and chronic bronchitis in individuals over the age of 40. Despite this knowledge, a second industrial complex was opened in 1963. In the Isozu district of Yokkaichi, the average concentration of sulfur dioxide was eight times that of unaffected districts. Taller smokestacks spread pollution over a wider area but did not resolve the problem; increased production also added to the volume discharged. Despite resistance, a third industrial complex was added in 1973, one of the largest petroleum refining and ethylene-producing facilities in Japan.

As the petrochemical industries continued to expand, local citizens' quality of life deteriorated. In the early years, heavy smoke was emitted by coal combustion, and parents worried about the exposure of schoolchildren whose playground was close to the emissions source. Switching from coal to oil in the 1960s seemed to be an improvement, but the now-invisible stack gases still contained large quantities of sulfur oxides, and more people developed respiratory diseases. By 1960, fish from the local waterways had developed such a bad taste that they were unable to be sold, and fishermen demanded compensation for their lost livelihood. By 1961, 48% of children under the age of six years, 30% of people over 60, and 19% of those in their twenties had respiratory abnormalities. In 1964, a pollution-free room was established in the local hospital where victims could take refuge and breathe freely.

Even so, two desperate people committed suicide in 1966, and 12 Yokkaichi residents who had been trying to resolve the problem by negotiation finally filed a damage suit against the Shiohama Kombinato in 1967. In 1972, the judge awarded the plaintiffs $286,000 in damages to be paid jointly by the six companies. This was the first case in which a group of Japanese companies was forced to pay damages, making other kombinatos vulnerable to similar suits.



In 2008, Japanese researchers Peng Guo, Kazuhito Yokoyama, Masami Suenaga, and Hirotaka Kida published the paper “Mortality and Life Expectancy of Yokkaichi Asthma Patients, Japan: Late Effects of Air Pollution in 1960–70s,” in the journal Environmental Health. The authors stated that laws were implemented to provide financial support to victims of Yokkaichi asthma. The petrochemical companies paid medical expenses based on the following requirements:

Public health role and response

In 1960, officials of Yokkaichi organized a committee to measure the pollution in the city. Three years later, the Japanese national government sent researchers to assess the situation. In 1965, the city established a medical aid program for its citizens. Two years later, several local citizens brought legal action against the petrochemical companies. Because of successful litigation by the Yokkaichi victims, the Japanese government enacted a basic antipollution law in 1967. Two years later, the Law Concerning Special Measures for the Relief of Pollution-Related Patients was enacted. It applied to chronic bronchitis and bronchial-asthma victims from Yokkaichi but also from Kawasaki and Osaka. In addition, national air-pollution standards were strengthened to require that oil refineries adhere to air pollution abatement policies.


The Japanese researchers Peng Guo and colleagues found in 2008 that the mortality rates for COPD and asthma for local residents were significantly higher than in the whole population of Mie Prefecture. In addition, they found that for all ages of residents, except for men between the ages of 80 and 84 years, their life expectancy was significantly reduced when compared to the entire population of Mie Prefecture. Even though pollution levels decreased substantially by the end of 1970s and no new cases had been reported since 1988, the Japanese researchers concluded that “Mortality and life expectancy were adversely affected in patients from Yokkaichi-city, despite the fact that the air pollution problem has been already solved.”

Bronchial asthma—
A respiratory disorder characterized by chronic inflammation of the airways.
Carbon monoxide—
With the chemical formula CO (where C stands for carbon, and O for oxygen), a colorless, odorless, and tasteless gas that is toxic to humans in higher than normal concentrations.
Chronic obstructive pulmonary disease (COPD)—
Also known by such names as chronic obstructive airway disease (COAD) and chronic obstructive respiratory disease (CORD), a respiratory disorder that causes both chronic bronchitis and emphysema.
Chronic bronchitis—
A respiratory disorder that causes chronic inflammation of the bronchi within the lungs.
Flue-gas desulfurization—
Technologies used to remove sulfur dioxide from exhaust flue gases of fossil-fuel power plants and other such processes.
Fossil fuels—
Any type of fuel, such as coal, natural gas, peat, and petroleum, derived from the decomposed remains of prehistoric plants and animals.
Pulmonary emphysema—
A progressive respiratory disorder that causes shortness of breath.
Sulfur dioxide—
With the chemical formula SO2 (where S stands for sulfur, and O for oxygen), a toxic gas with a strong, irritating smell; in nature it is released from spewing volcanoes and it is also released by human-producing industrial processes.



See also Air pollution ; Asthma ; Bronchitis ; Chronic obstructive pulmonary disease ; Smog .



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American Medical Association, 515 N. State St., Chicago, IL, 60654, (800) 621-8335, http://www.ama-assn.org .

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World Health Organization, Avenue Appia 20, Geneva, Switzerland, 1211 27, 41 22 791-2111, Fax: 41 22 791-3111, cdcinfo@cdc.gov, http://www.who.int/en .

Frank M. D'Itri
Revised by William A. Atkins, BB, BS, MBA

  This information is not a tool for self-diagnosis or a substitute for professional care.