Update:April 1, 2010

(3) Air Pollution and Public Health Problems

1.Construction of Petrochemical Complexes and the Outset of Pollution

Following at the heels of water pollution which had damaged fisheries to a great extent, problems of air pollution such as smoke and soot or offensive odor had become a significant issue. Around 1959, when the first petrochemical complex started operation, asthma and other respiratory disease afflictions broke up among the people living in the neighborhood of the complex, particularly in the Shiohama District and the Isozu District. Since then, a lot of attempts had been made to locate the origin of the diseases. However, at the beginning, their aim remained uncertain since the causal relation of air pollution to those diseases had not yet been identified, The earliest effort was the field measurements of sulfur dioxide (SO2) concentration and dustfall in the vicinity of the complex carried out by Mie University from November 1960. The measurements were originally performed with manual instruments and then switched to automatic in 1962.
As stated in their report of 1961, the Isozu District was considerably polluted especially in the wintertime since the area turns into the leeward due to the seasonal northwest wind blowing from the direction of the complex. Sulfur dioxide concentration in Isozu District sometimes reached a level of 1ppm on the hourly average (See Figure 2-2) and 0.1ppm on the annual average, the latter level in, particular, is over 10 times as high as the current level (0.008ppm). In the summertime, on the other hand SO2 concentrations in specific parts of downtown Yokkaichi was raised to extraordinary levels as the wind blows southeast from the direction 0f the complex (See Figure 2-3).
Furthermore, health screening of the residents conducted in parallel with the above measurements produced the finding that people suffering from respiratory organ illness were mainly concentrated in the vicinity of complexes. The had encouraged further investigations based on the assumption that SO2 was one of the major contributors to the outbreak of those diseases. Complaints from the residents concerning pollution problems drastically increased since around 1963 when the second petrochemical complex started its operation full-scale. The pollution-related complaints had initially centered on the offensive odor. Besides SO2 which stays under the human's olfactory threshold when low in concentration, hydrogen sulfide (H2S) and methylmercaptan derived from crude oil, aldehydes from petrochemical process, and other malodorous substances leaking from the factories had immediately become targets. To make matters worse, the second petrochemical complex had broken down in its trial run and released a great amount of malodorous runoff thereby inciting residents to more aggressive actions of complaints or claims.