An epidemiological survey has been carried out on the relationship between air pollution and mortality in Yokkaichi area covering from 1961 to 1970.
The death rate from obstructive respiratory diseases, especially bronchial asthma and emphysema, increased in the polluted area since 1966 and a significant difference in death rates was noticed among the polluted and non-polluted areas.
Mortality from these diseases obviously correlates with the degree of sulphur dioxide concentrations in 1968 and 1969.
The age-distribution of deaths from obstructive respiratory diseases was studied during a ten-year-period.
Deaths from bronchial asthma occurred at younger ages in the polluted areas, while deaths from emphysema were not encountered among women in the non-polluted areas.

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A public relief-system has been established since 1965 in Yokkaichi for patients whose symptoms are regarded to have been caused by air pollution.
To date 710 patients came under this relief-system.
Results of epidemiological research on the present state of these patients:
1) Incidence of chronic obstructive pulmonary diseases had a tendency to increase in relation to the degree of air pollution.
2) Incidence in infants and old age groups was higher than in other age groups, and in males about twice that of females.
3) In Isozu, the highest polluted area in Yokkaichi, the number of new patients increased until 1965, and gradually decreased in parallel with a decrease in pollution level following construction of higher smoke stacks.
Bronchial asthma incidence peaks occurred at the beginning of air pollution, while peaks of chronic and asthmatic bronchitis occurred affer 2 to 3 years.

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This review describes the outline of Yokkaichi-asthma which has been occured in Yokkaichi-area. Since 1961, in parrallel with industrial activities, abnormal growing of bronchial asthma has been observed and called with the name of Yokkoichi-asthma in relation of air pollution. The review containes the main results which have been published and unpublished, and also containes discussion and speculation on its etiology. Authors also pointed out the possibility of same “asthma” due to air pollution in other polluted areas.

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We have investigated the health effects of air pollution during the perinatal period through the records of birth, immature foetus birth, still-birth and death certificates from 1968 to 1975 in Yokkaichi area. Following result was obtained:
The relationships between the surfur dioxide level and immature foetus birth rate, infant death rate and still-birth rate were relatively small and correlation coefficients betwen sulfur dioxide level and these rates had statistically no significant difference.

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In order to clarify the relationship over time, between air pollution and chronic obstructive lung diseases in Yokkaichi, Japan, certificates of death from disease for the years 1963 to 1979 were studied.
The following results were obtained:
1) Several years after the frequency of chronic obstructive lung diseases had increased, the mortality rates from such diseases also began to rise.
2) With the reduction of pollution as a result of measures taken to control its sources, the mortality rate for asthma fell first, and then, those for chronic bronchitis and emphysema also fell to the levels observed in the control areas.
3) When levels of pollution in the polluted areas were highest, deaths from bronchial asthma occurred at increasingly younger ages.

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To investigate the effects of air pollution on lung cancer, we carried out surveys of the rates for visits to physicians using receipts from the National Health Insurance Plan and of lung cancer mortality rates using death certificates.
The results were as follows:
1) The rates of visits to physicians for lung cancer were proportional to the degree of air pollution within a given area, but when compared with the control area, no significant difference was found.
2) Several years after air pollution increased markedly in Yokkaichi City, the lung cancer mortality showed rising tendencies, but no significant correlation between lung cancer mortality and the level of specific pollutants was found.
Compared to the control area, lung cancer mortality rates were slightly higher and increasingly younger ages of deaths from lung cancer in the polluted area were observed.
3) Furthermore, a higher death rate from lung cancer was found among those smoking more than 21 cigarettes per day than among nonsmokers.

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The effects of air pollution were investigated on high school students in Yokkaichi city, inquiring into the consequential effect to the children, as ten years had already passed since the episode of air pollution occurred there.
The following results were obtained.
1) A greater part of students with the histories of chronic bronchitis and asthmatic bronchitis during childhood had more favorable progress as compared to the older age groups, even if they have lived in the polluted area for a long time. However a part of students with bronchial asthma had an unfavorable progress.
2) The prevalences of chronic bronchitis (Fletcher) and asthmoid attack, were not much different from those in non-polluted area.
A further follow up investigation should he done, as many of the students were seen complaining of persistent cough and phlegm in polluted area.

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The prevalence of respiratory diseases, and bronchial asthma in particular has increased in Yokkaichi with the worsening in air pollution during the period of 1961 to 1962.
A Public Relief System was established in 1965 in order to assist sufferers.
It was revised in 1973 based on laws to deal with Compensation for Victims of Environmental Pollution.
The fiscal year 1980 was the year in which pollution victims were to be re-examined.
The results of medical examinations of 488 bronchial asthma victims in the Yokkaichi area were examined and the following results were obtained:
1) The onset of asthma coincided with periods when there was marked air pollution in Yokkaichi.
2) Asthma due to allergic reactions was found in most younger victims age group (under 39 years old) and infectious asthma in many older victims (over 40 years old).
3) Asthma caused by environmental pollution is characteristic of advanced age and is often complicated by clinical symptoms such as chronic cough and the discharge of sputum.
A low percentage have eosinophilia and low show positive intradermal reactions to house dust.
4) According to auscultation and lung function tests, symptoms appeared to be reversible in many of younger cases, but attacks were repeated or symptoms indicated permanent damage in most of the advanced age group.

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We have mentioned the problems with the Law Concerning Compensation for Health Damaged by Public Hazards.
This system makes it the point to pay compensations to patients in accordance with the degree of impairment.
We have studied some problems that should be solved by actually examining the degree of impairment of the patients.
Where the medical certificate on the symptoms of the respiratory system issued by a physician in charge is concerned, the rate of agreement between the control classification submitted by the physician in charge and the degree of impairment decided by the examination council differs greatly from one physician to another.
Particularly, there are some physicians who show an extremely poor rate of agreement.
These facts indicate that the diagnosis of a physicians is greatly influenced by physician's way of understanding the standard rather than by the influence of complications and other reasons.
We think it necessary to take some measures to improve such a situation in the future.
Referring to the examination on the respiratory function, in the case of asthma in the young age group, even with patients showing an index of 70 or more which corresponds to the “outside class” according to existing standard, many are actually receiving the medical treatment for that disease.
In this age group, none comes under this standard unless the examination is performed during the attack, and thus, there is a need to ease the restriction by creating a standard by age.
In the advanced age group, meanwhile, there are many patients in whom the index is 35 or less but the partial pressure of oxygen in the arterial blood is good.
This suggests that this index is influenced by complications and the situation in which the measurement is made.
We wonder if it is not better in this age group to expand further the scope of subjects for the examination on arterial blood (at present, those with the index of 35 or less) and to use this examination in making a decision over a wider scope of ranking.

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For the purpose of studying the influence of air pollution that causes pulmonary tuberculosis, the authors investigated the relationship between the level of pollution by area in Yokkaichi on the one hand, and prevalence, incidence, the visit rate to the physician and death rate of pulmonary tuberculosis on the other hand.
Prevalence and incidence showed a similar pattern and were influenced greatly by economic factors of the area as observed in the relationship with the on-relief rate, but the influence of air pollution was not found under the level of the pollution as shown in Table 1.
The visit rate to the physician taken by those insured by the National Health Insurance Plan was influenced more or less by social factors such as the density of medical institutions and density of population in addition to the above-mentioned economic factor, but had nothing to do with the air pollution.
Death due to pulmonary tuberculosis was caused by sulphur dioxide; when the mean concentration for three consecutive days surpassed 60ppb, the probability of the death on the last day became higher, the differrence being statistically significant at 5 per cent compared with days on which the concentrations were 19ppb or less.

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大気汚染による健康影響を把握するために, K市医師会はモニター方式による健康影響調査を行っている.この方式は, K市医師会会員から選ばれたモニター医師が, 毎月1回, 特定呼吸器疾患の有症者と当日の総受診件数をK市医師会に報告するものである.本研究は, K市におけるモニター方式により得られた健康影響指標の有用性を明らかにすることを目的として, 1973年4月から1983年3月までの10年間に, この方式によって得られた健康影響指標と環境指標との関連を相関分析と多変量解析法を用いて検討した.健康影響指標は, 特定呼吸器疾患のうち喘息性気管支炎, 慢性気管支炎及び気管支喘息の対総受診件数比及び対K市全人口比を用い, 環境指標はK市によって行なわれた大気中の環境濃度を用いた.健康影響指標と環境指標との年次変化の相関分析を行った結果, 有意の相関が認められた指標と認められなかった指標とがあり, 複数の環境指標と健康影響指標との関連を総合的に検討する必要を認めた.重回帰分析法を用いて複合的な大気汚染と健康影響指標との関連を検討した結果, 喘息性気管支炎と慢性気管支炎は説明が可能であったが, 気管支喘息については説明不能であった.そこで, 正準相関分析法を用いて健康影響指標を各々の疾患別にではなく健康影響指標群として, また, 環境指標も各々の環境濃度ではなく環境指標群として, 両群間の相関を求めたところ有意の相関が認められ, 正準得点散布図から健康影響指標群の動向と環境指標群の動向は一致している事が認められた.以上の結果より, K市医師会がモニター方式によって得た健康影響指標は, 環境指標との関連で健康影響把握に有用であることが明らかになった.

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