Yokkaichi Asthma: The Worst Air Pollution Ever in Japan

Among the four infamous pollution diseases that most Japanese know, Yokkaichi asthma is the only disease caused by air pollution (other three diseases caused by water pollution are Itai-Itai disease, Minamata Disease, and Niigata Minamata Disease). As the name indicates, it is asthma caused by air pollution in Yokkaichi. Yokkaichi is a city with the largest population in Mie Prefecture and produces ¼ of the petroleum in Japan and other diverse products, such as porcelain, cars, textiles and chemicals (“4 Big Pollution Diseases of Japan.”). It owes its thriving economy to the port that was built in 1872 and in 1897 it was afforded ‘modern city’ status; its future was assured. After the World War II, the city became more reliant on reliant on chemical production and plants that arose all over the city.

Just like many northern cities of England or those of the “Rust Belt” in the USA, industrial companies carried out the production and processing of hazardous materials with insufficient respect for the local environment, and the burning of petroleum products in Yokkaichi had reached high enough levels to cause some incidents of severe air pollution by the early 1960s (“Yokkaichi Air Pollution – 1961-1988.”). And, some scholars think that the pollution started as early as the mid-1950s (“Yokkaichi asthma, Japan.”). The first case of pulmonary disease related to industrial pollution was reported in 1961, and people started to mask their faces with handkerchiefs every day. As levels of sulfur dioxide in the air became dangerously high, the local population began to suffer from seriously detrimental effects of the pollution on the respiratory systems. The companies’ initial efforts to alleviate the problem were awfully inadequate. The height of industrial chimneys was raised in order to spread the pollutants over a larger area; however, this effort did little to help (“Yokkaichi Air Pollution – 1961-1988.”). The smog continued to increase and soon hundreds of people were diagnosed with respiratory diseases, such as chronic obstructive pulmonary disease, chronic bronchitis, pulmonary emphysema, and bronchial asthma. In Isozu, where air pollution was most severe, incidence of asthma reached up to 2.5% of total population in 1964 (“Yokkaichi asthma, Japan.”). In 1970, a class-action lawsuit against the biggest polluter, Showa Yokkaichi Oil, finally led to an effective action. In 1972, as a result of lawsuits, the companies started to conduct a series of counter measures based on an area-wide total emission control system, such as a process of gas desulphurization. The harmful chemicals were removed from the atmosphere and the last case of pulmonary disease linked to local heavy industry was reported in 1988 (“Yokkaichi Air Pollution – 1961-1988.”).


Researchers report that two deaths have been attributed to asthma caused by the smog, and research indicates that mortality rates from chronic obstructive pulmonary disease were between ten and 20 times greater in Yokkaichi than in the rest of Mie Prefecture when there was air pollution. Moreover, a study reported that, even after the air pollution problem was solved, mortality rates for chronic obstructive pulmonary disease and asthma in patients from Yokkaichi-city were significantly higher than in the whole population of Mie Prefecture. Additionally, many more people, including children as young as 7 years old, died of respiratory diseases, but they have not been acknowledged by the authority. Also, a number of people who were sick because of the pollution committed suicides, becoming exhausted from the pollution.

Among the four major pollution diseases, Yokkaichi asthma is distinctive in several aspects. One of the unique features is the local and prefectural governments’ responsibility. They prioritized the economic growth over the public health and helped the companies. These facts were reviewed in a court case, and they were also sued by victims. A part of reason that they supported the companies is because there had not been as bad pollution diseases in Japan as Yokkaichi asthma, so the mayor, who lacked scientific knowledge, genuinely did not know the smog could cause diseases. Another distinctive characteristic of Yokkaichi asthma is the fact that pollution happened in an urbanized area with strong economic development, compared to other three diseases that took places in non-urban areas. Politicization is one more unique characteristic of Yokkaichi asthma. This issue quickly became political; the focus was a conflict between conservatives, which included Liberal Democratic party and business community, and liberals, which included political parties that supported the victims, such as the Japanese Socialist party, the Democratic Socialist party, the Komei party, and the Japanese Communist party. After the issue, the conservatives lost their political power, allowing the liberals to gain power. Furthermore, this issue made the government, which was controlled by the Liberal Democratic party at the time, to establish the Japanese Environmental Agency in 1971.

With an aim to develop and introduce pollution prevention measures, the government of Mie prefecture created the Yokkaichi Area Pollution plan with different prevention and control measures, which was implemented in eight stages and ended in 2010. Following the plan, the local government installed new infrastructure, such as an improved public sewage treatment system and the establishment of green areas. Also, businesses developed pollution prevention machinery, such as desulfurization equipment. The public and private sectors invested 983.7 billion yen (approximately US$8.2 billion) in total to improve the environment (Latsaphao). By taking these steps, air pollution has never returned to the area, and Yokkaichi city is now striving to become an environmentally advanced city, spreading the word of its success in pollution control to the rest of the country and overseas as well.


“4 Big Pollution Diseases of Japan.” Ecoist Magazine. Last modified November 16, 2015. https://ecoistmag.wordpress.com/2015/11/16/4-big-pollution-diseases-of-japan/

“Yokkaichi asthma, Japan.” Environmental Justice Atlas. Last modified November 27, 2016. https://ejatlas.org/conflict/yokkaichi-asthma-japan

“Yokkaichi Air Pollution – 1961-1988.” Devastating Disasters. n.d. https://devastatingdisasters.com/yokkaichi-air-pollution-1961-1988/

Latsaphao, Khonesavanh. “Pollution Disappears from Yokkaichi City.” Japan Up Close. Last modified September 3, 2015. http://japanupclose.web-japan.org/other/o20160115_1.html