ABSTRACT
Japan is located in East Asia, comprising the four main islands and more than 6000 smaller islands with land space of 377, 960 km2� The total population size is approximately 127 million, and the proportion of elderly population to total population is 25%� Concentration of the population in urban areas is still ongoing, and more than half of the population lives within three major urban areas� For land use, 66�3% is woodland, 12�1% is agricultural, 5�0% is residential, 3�6% is transport, and 3�5% is water (Statistics Japan, 2014)�
The Japanese islands extend from north to south as well as east to west over 2000 km and most parts of them are in the temperate zone with four distinct seasons, but the north is cool and the south is subtropical� Climate is different between the Pacific coast side and the Sea of Japan side� Pacific Ocean climatic zone is characterized by hot and humid days during summer because of seasonal south wind from the Pacific Ocean� In the Sea of Japan climatic zone, cold monsoon in winter from the Siberian anticyclone, that is, westerlies, brings heavy snowfalls while relatively dry during summer� Hokkaido climatic zone is also cold in winter and cool in summer� In addition, there are three other climatic zones; Central Highland, Seto Inland Sea, and Ryukyu Islands zones� Annual average (minimum to maximum) daily temperatures of major cities are 9�2 (5�8-13�0) degrees Celsius in Sapporo, 17�1 (13�6-21�0) in Tokyo, 17�1 (13�4-21�5) in Osaka, and 17�7 (14�3-21�8) in Fukuoka, respectively�
Going back to the world history, modernization had brought a good and a bad side for society� Industrialization of Japan started in 1890s, and rapid economic growth has been achieved around 1950-1970s� During that time, the life expectancy prolonged surprisingly: life expectancy for males improved from 58�0 in 1950 to 71�7
3�1 Background �����������������������������������������������������������������������������������������������������65 3�2 Health Effects �������������������������������������������������������������������������������������������������66
3�2�1 Three-Prefecture Cohort Study ����������������������������������������������������������66 3�2�2 NIPPON DATA 80 ����������������������������������������������������������������������������� 67 3�2�3 Japan Public Health Center-Based Study ������������������������������������������ 67
3�3 Exposures, Risk Assessment, and Risk Management ������������������������������������ 70 3�4 Conclusion ������������������������������������������������������������������������������������������������������ 75 References ���������������������������������������������������������������������������������������������������������������� 75
in 1970 and that for females did change from 61�5 to 76�9� On the other hand, breakneck industrialization and urbanization caused severe air pollution episodes in Japan� Around 1955-1965, air pollution episodes with respiratory problems were experienced among industrial area residents due to inhalation of soot dust and sulfur dioxide (SO2) emitted from coal-burning plants and oil-refining plants� The most well-known SO2 episode in Japan was occurred in Yokkaichi of Mie prefecture, which is located in the Pacific coast side of the central Japan� Numerous petrochemical plants started their operation in 1960, and residents in some areas started to complain of asthmalike symptoms just in a few years� Annual emission of sulfur oxides was estimated to be 130-140 thousand tons in 1963-1964� The Yokkaichi Air Pollution Lawsuit had been filed in 1967 regarding the legal causal relationship between air pollution mainly due to SO2 and the infringement of the right of health as well as the joint responsibility of six companies in the area, and the decision was made to find joint responsibility of six companies based on epidemiological causality (Yoshida et al�, 2007)�
To control such situations legally, the Act Concerning Control of Soot and Smoke Emission was enacted in 1962� For basic national policy against environmental pollution, the Basic Law for Environmental Pollution Control was enacted in 1967, leading to establishment of the Air Pollution Control Act in 1968, aiming at protecting the nation’s health and to conserve the human environment� Basic framework for legal pollution control was shaped, including setting the environmental quality standard (EQS), monitoring environmental quality, implementing countermeasures for hazardous pollutants, and stipulating allowable limits of emission� In Yokkaichi, introduction and implementation of total emission control for SO2 had largely contributed to reducing pollution level in the region� Environmental air quality standard for SO2 was first set as not exceeding annual average for hourly values of 0�05 ppm in 1969, and revised to (1) daily average for hourly values of 0�04 ppm, and (2) hourly value of 0�1 ppm� The Basic Law for Environmental Pollution Control was revised to the Basic Environment Law in 1993, in which formation of the environmental conservation society and the global environmental protection were added as basic policy (Ministry of the Environment [MOE], 2014)�
In 1970s, accompanying progress in urbanization, pollution with photochemical oxidants, that is, urban ozone, has been recognized as next air pollution issue, followed by nitrogen oxides (NOx)� Regulations on motor vehicle exhausts were stipulated in the Air Pollution Control Act in 1978, and the Automobile NOx Act was enacted in 1992�
This chapter describes current status and issues of air pollution control in Japan, mainly focusing on particulate matter�
Three Japanese epidemiologic studies on health effects of long-term exposure to particulates have been published�
The aim of this study (Katanoda et al�, 2011) was to investigate health effects of air pollutants on mortality, especially focusing on respiratory diseases� Target population was 100,629 adults over 40 years old (male 46%) in six regions of three
prefectures (Miyagi, Aichi, and Osaka)� The baseline survey was conducted in 1983-1985, and the participants had been followed for 10-15 years� In this study, concentration of suspended particulate matter (SPM), SO2, and nitrogen dioxide (NO2) was continuously measured� In the statistical analysis, particulate matter with an aerodynamic diameter of 2�5 μm (PM2�5) concentration was estimated by multiplying SPM concentrations by a factor of 0�7� Average concentrations prior to the study (1974-1983) were 16�8-41�9 µg/m3 for PM2�5, 2�4-19�0 ppb for SO2, and 1�2-33�7 ppb for NO2, respectively� The major finding of the study was that lung cancer mortality was significantly associated with SO2, NO2, and SPM concentration, adjusting for major potential confounders, including smoking� The hazard ratios (95% confidence interval [CI]) per 10-unit increase in PM2�5, SO2, and NO2 were 1�24 (1�12-1�37), 1�26 (1�07-1�48), and 1�17 (1�10-1�26), respectively� Other respiratory diseases were also associated with SO2 and NO2 in females, but no association was observed with SPM�
National Integrated Project for Prospective Observation of Noncommunicable Disease and Its Trends in the Aged 80 (NIPPON DATA 80) is a prospective cohort study of the participants of the National Survey on Circulatory Disorders in 1980 (Ueda et al�, 2012)� The study population was the participants of the National Nutritional Survey of Japan, which has been performed using weighing record method for three consecutive days to each household in a large-scale sample of representative Japanese from 300 randomly selected districts in Japan� In this report, exposure information was obtained from the nearest monitoring station to each census area using geographic information system (GIS)� Averaged particulate concentrations (defined as particles with a 100% cutoff level of aerodynamic diameter 10 µm, which can be considered to be particles of less than 7 µm with a 50% cutoff level) measured at the corresponding station were assigned to each participants residing in the census area� Study subjects were 7250 residents aged 30 years or more, randomly selected 232 census areas in 1980, and were followed up until 2004� The Cox proportional hazard model was applied adjusting for sex, age, body mass index, blood pressure, total cholesterol, blood glucose, smoking categories, drinking categories, and municipality population size� As a result, numbers of deaths were 1716 for all-cause deaths, 571 for cardiovascular deaths, 116 for coronary deaths, and 250 for stroke deaths, but no significant association was observed between long-term exposure to particulates and cardiovascular mortality risk�
The Japan Public Health Center (JPHC)-based study (Nishiwaki et al�, 2013) is a prospective cohort study lead by the National Cancer Research Center of Japan in collaboration with 11 JPHCs nationwide� Cohort I started in 1990 with five centers, and Cohort II initiated in 1993-1994 in six centers� Among more than 100,000
participants, 78,057 participants (37,121 males, 40,936 females) aged 40-59 in nine areas where ambient air monitoring stations were equipped near to the public health center were included in the mortality analysis� For incidence analysis, 62,142 (30,238 males, 31,904 females) from seven areas were subject to analysis� Average of annual particulate concentrations (defined as the same as NIPPION Data80 study) during the study period were ranged 17�2-43�7 µg/m3� After controlling for major potential confounders including age, sex, smoking, body mass index, alcohol consumption, and blood pressure, no significant association with particulate level was observed in mortality analysis, but risks having coronary heart disease and myocardial infarction were increased in incidence analysis, particularly among smokers� Adjusted hazard ratios per 10 µg/m3 increase in particulates were 1�39 (95% CI: 1�01-1�93) for coronary heart disease and 1�52 (1�08-2�13) for myocardial infarction among smokers� Similar results were obtained for females, although the associations diminished when one center area was excluded from the analysis�
There exist methodological issues to examine long-term effects of particulate matter on cardiovascular diseases� First, distribution pattern of coronary heart disease and stroke is contradictory between Japan and Western countries because of different distribution patterns of major risk factors such as serum cholesterol and prevalence of obesity� The leading cause of cardiovascular deaths is stroke in Japan, while it is coronary heart disease in Westerns� Second, different spatial distribution patterns of cardiovascular mortality and air particulate matter concentration between urban and rural areas makes it more difficult to conduct a valid epidemiological study in Japan because incidence and mortality of stroke tend to be high in rural areas indicating that general risk factors are more prevalent among rural residents while particulate matter levels are to be high in urban areas in Japan� A valid epidemiological study should be conducted in Japan, in which cardiovascular risk factors are comparable except for particulate matter concentrations�
For short-term effects of particulate matter, Ueda et al� reported the results of time-series and case-crossover analyses in the 20 cities of Japan where PM2�5 concentration has been monitored (Ueda et al�, 2009; MOE, 2008)� Mortality data between January 1, 2002, and December 31, 2004, were obtained through the centrally collected death certificates in the Ministry of Health, Labor, and Welfare in which the cause of death was coded in the National Vital Statistics Bureau� Air quality monitoring data were PM2�5 measured by tapered element oscillating microbalance (TEOM), common pollutants, temperature, and humidity� Risk estimates corresponding to PM2�5 increase in 10 µg/m3 were calculated for each city, and then unified risk estimate was obtained with both single-pollutant model and multipollutant model using the generalized additive model� In a singlepollutant model, unified risk ratios for 10 µg/m3-increase were 1�002 (95% CI: 0�998-1�006) for all-cause death, 0�999 (0�990-1�007) for respiratory death, and 1�001 (0�993-1�009) for cardiovascular death, respectively (Lag = 0)� Risk ratio for respiratory death was significantly increased (1�010) at lag 3� Risk ratios of daily mortality for 10 µg/m3-increase in PM2�5 were exceeded 1�0 in some cities, and its unified risk ratio was significantly increased for respiratory deaths� However, no increased risk was observed for cardiovascular deaths� The 98th percentile of 24-hour concentrations of PM2�5 ranged 31-55 μg/m3 for overall analysis, and the
98th PM2�5 concentration ranged 44-47 μg/m3 in the region where daily mortality was significantly increased�
The fatality rate ratios of cerebro-cardiovascular events with relation to daily level of ambient air pollutants were reported using the stroke and acute myocardial infarction (AMI) registry of Takashima county in Shiga prefecture, which is located in the central part of Japan (Turin et al�, 2012a)� During the study period of 1988-2004, 307 (153 in men and 154 in women) cases had fatal stroke within 28 days of onset among 2038 first-ever stroke cases� The number of fatal AMI cases within 28 days of onset in the same period was 142 (men: 94 and women: 54) among the 429 first-ever AMI events� A Poisson regression model was applied to calculate fatality rate ratios associated with stroke and AMI on a day with higher level of pollutants compared with a day with the lowest level� Daily average pollutant concentration, including SPM, NO2, SO2, and Ox (photochemical oxidants), was measured at the nearest monitoring stations, and then all 6210 data of daily average values were divided into quartiles� Multiple-pollutant models with several possible confounders were constructed� Mean values of daily average concentrations were 26�9 µg/m3 for SPM, 3�9 ppb for SO2, 16�0 ppb for NO2, and 28�4 ppb for Ox� Fatality rate ratios for stroke were significantly increased with relation to NO2 levels while other pollutant levels, including SPM, did not show any association with fatality rate ratios for stroke or AMI�
In addition, time-stratified, bidirectional, case-crossover analysis was applied to the same dataset using the distributed lag model to estimate the effect of pollutant exposure 0-3 days before the onset controlling for meteorological factors (Turin et al�, 2012b)� The authors concluded that, although an association between SO2 and hemorrhagic stroke was observed, they found inconclusive evidence for a short-term effect of air pollution on the incidence of other stroke types and AMI in Japan�
Asian dust, transported from the desert areas of China and Mongolia and called kosa in Japan, is also public concern for its possible health effects� In 2014, two studies were reported regarding this issue� A correlational study of subjective symptoms and serum immunoglobulin E (IgE) levels with relation to 3-day Asian dust event in April of 2012 among 25 healthy volunteers was done in Yonago of Tottori prefecture, located in the Sea of Japan side of the western part of Japan (Otani et al�, 2014)� During the event period, Asian dust-related symptoms (nasal, pharyngeal, ocular, respiratory, and skin) were recorded daily� Serum nonspecific IgE and 33 allergenspecific IgEs were also measured after the dust event� The authors suggested the potential associations between nasal symptoms and fungal allergen IgE level and Asian dusts�
A time-stratified, case-crossover study to examine the association between Asian dust and the incidence of AMI was done in Fukuoka, Kita-Kyusyu, and Kurume cities of northern Kyusyu in western Japan (Matsukawa et al�, 2014)� A conditional logistic regression analysis was done with 3068 consecutive patients who were hospitalized due to AMI from four different AMI centers between April 2003 and December 2010 to estimate the risk of AMI associated with occurrence of Asian dust event, controlling for ambient temperature and relative humidity� Asian dust event was reported when its visibility reduced to less than 10 km by ground-level
observation at the local meteorological observatory� Odds ratio [OR] of AMI incidence was significantly associated with Asian dust event with 4 days of lag (OR 1�33, 95% CI: 1�05-1�69)� The association remained significant with cumulative lags of 0-4 days (OR 1�20, 95% CI: 1�02-1�40)�
The EQS is defined pursuant to the Article 16 of the Basic Environment Law as follows:
1� With regard to the environmental conditions related to air pollution, water pollution, soil contamination, and noise, the government shall respectively establish EQSs, the maintenance of which is desirable for the protection of human health and the conservation of the living environment�
2� In the event that the standards referred to in the preceding paragraph establish more than one category and stipulate that land or water areas to which those categories are to be applied should be designated, the government may delegate to the prefectural governors concerned the authority to designate those land or water areas, in accordance with Cabinet Order�
3� With regard to the standards set forth in point 1, due scientific consideration shall always be given and such standards shall be revised whenever necessary�
4� The government shall make efforts to attain the standard provided in point 1 by comprehensively and effectively implementing policies concerning environmental pollution control which are set forth in this chapter�
MOE set six EQSs for classical pollutants including PM2�5 and five EQSs for hazardous air pollutants including dioxin in Japan (Table 3�1)� For PM2�5, its EQS was set (1) less than or equal to 15 µg/m3 as annual average and (2) less than or equal to 35 µg/m3 as daily average (Table 3�2)� The expert committee on PM2�5 air EQS summarized its discussion as follows:
• There exists the health risk of PM2�5, but no threshold was detected in a population level from exposure-response analysis of the existing epidemiological studies, and residual risk may exist even in background regions in Japan, where annual mean PM2�5 concentrations ranged 6-12 μg/m3 although health risk cannot be quantified in such lower level�
• Although discrepancy of cardiovascular effects between United States and Japan can be interpreted by differences in common cardiovascular risk factors or disease pattern, toxicological and epidemiological findings have been accumulated to support cardiovascular effects of PM2�5 and it is difficult to fully explain the discrepancy at present, such as by differences in common non-PM risk factors, why we Japanese cannot observe increased cardiovascular risks of PM�
• Size of PM2�5 risk is relatively small but the risks should be reduced from the public health point of view, and it is noteworthy that risks of
cardiovascular diseases could be apparent even in Japan in the future if prevalence of cardiovascular risk factors become comparable with that of Western nations�
To maintain air qualities, the Air Pollution Control Act is placed under Basic Environment Law� Protection of the public health and preservation of the human
TABLE 3.1 Air Environmental Quality Standard (EQS) in Japan
TABLE 3.2 Environmental Quality Standard (EQS) for PM2.5 (MOE Notification, September 9, 2009) I. EQS for PM2.5 1� Annual average of less than or equal to 15 µg/m3
living environment with respect to air pollution are provided by (1) controlling emissions of soot and smoke, volatile organic compounds (VOCs) and particulate by setting emission standards from the business activities of factory and business establishments; (2) promoting various measures concerning hazardous air pollutants; (3) setting allowable limits for automobile exhaust gases; and (4) monitoring of the level of air pollutions� It also provides a liability regime for health damage caused by air pollution from business activities to help victims of air pollutionrelated health damage�
The emission standards (general emission standard, special emission standard, stricter emission standard, and total mass emission control standard) are set for “soot and smoke” emitted from the business activities of factory and business establishments, including sulfur oxides generated by the combustion of fuel or other items, soot and dust generated by the combustion of fuel or other items or by the use of electricity as a source of heat, cadmium and its compounds, chlorine and hydrogen chloride, fluoride, hydrogen fluoride and silicon fluoride, lead and its compounds, and nitrogen oxides� VOCs such as painting, cleaning, or printing solvents generate photochemical oxidants and particulate matter, and have been subject to regulation since amendment of the Air Pollution Control Law in 2004� Control efforts for VOC emissions have been done through voluntary efforts by business activities with legal restrictions, and significant reduction had been achieved by FY 2010� Emissions of particulates including asbestos from the business activities of factory and business establishments are also regulated under the Act�
The “hazardous air pollutant” is defined in this Act as any substance that is likely to harm human health if ingested continuously and that is a source of air pollution other than soot and smoke or particulates specified in the Act� There are 248 substances present that are being classified as hazardous air pollutants, and 23 of those are classified as priority substances� Those are acrylonitrile, acetaldehyde, arsenic and its inorganic compound, benzene, benzo(a)pyrene, beryllium and its compound,1,3-butadiene, chloroform, chromium(III) and its compound, chromium(VI) compound, 1,2-dichloroethane, dichloromethane, dioxin, ethylene oxide, formaldehyde, manganese and its compound, mercury and its compound, methyl chloride, nickel compound, tetrachloroethylene, toluene, trichloroethylene and vinyl chloride monomer� Among those, air EQS has been set for benzene, dichloromethane, tetrachloroethylene, trichloroethylene, and dioxin, and the emission standards have also been set for benzene, tetrachloroethylene, and trichloroethylene� A special law, Law Concerning Special Measures against Dioxins, was enacted in 1999 for dioxin� The guideline values have been set for nine hazardous air pollutants (Table 3�3)� The value is not the standard value (EQS) but the reference value to reduce potential human health risks as it could be set even if scientific evidence is limited to quantify dose-response relationships between exposure to hazardous air pollutant and health�
To control motor vehicle exhaust emissions, various countermeasures are being implemented by MOE as follows: (1) controls on emissions per vehicle; (2) enactment of the Law Concerning Special Measures for Total Emission Reduction of Nitrogen
Oxides and Particulate Matters from Automobiles in Specified Areas and the Act on Regulation, and so on of emissions from nonroad special motor vehicles; and (3) encouraging use of low-pollution vehicles�
Monitoring of air quality has been done through national and local (prefectural) monitoring stations across the country for both classical pollutants and hazardous air pollutants� The number of monitoring stations is more than 1500 for general monitoring and about 400 for roadside monitoring� Recent results (FY 2012) of air quality monitoring of classical pollutants and some hazardous pollutants with EQS or guideline value are shown in Tables 3�4 and 3�5� For photochemical oxidants, its annual mean of the daytime maximal hourly values has continued to increase gradually since 1980s (Figure 3�1), but various countermeasures against VOC and other substances have been taken to lower its daytime concentration�
TABLE 3.3 Guideline Values for Nine Hazardous Air Pollutants
TABLE 3.4 Results of Air Quality Monitoring of Classical Pollutants in FY 2012
FIGURE 3.1 Trend of annual mean of daytime maximal hourly values for photochemical oxidants concentration in Japan: FY 1976-2012�
TABLE 3.5 Results of Air Quality Monitoring of Some Hazardous Pollutants with Environmental Quality Standard (EQS) or Guideline Value in FY 2012
Modernization of the society (i�e�, industrialization and urbanization) brought various good things for human health such as better access to medical care or improvement of infant and maternal mortality which lead to longevity� However, as Japan had already experienced, uncoordinated rapid industrialization and urbanization resulted in environment pollution and poor air quality� Nowadays, environmental issues are occurring beyond the borders of one country and into neighboring areas� In Japan, PM2�5 and photochemical oxidants are the two major remaining air quality issues to be worked on, but we also would like to share our experiences and technologies with the Asian countries to solve air quality issues around this region�
Katanoda, K�, Sobue, T�, Satoh, H�, Tajima, K�, Suzuki, T�, Nakatsuka, H�, Takezaki, T�, Nakayama, T�, Nitta, H�, Tanabe, K�, and Tominaga, S� (2011)� An association between long-term exposure to ambient air pollution and mortality from lung cancer and respiratory diseases in Japan� J Epidemiol, 21, 132-43�
Matsukawa, R�, Michikawa, T�, Ueda, K�, Nitta, H�, Kawasaki, T�, Tashiro, H�, Mohri, M�, and Yamamoto, Y� (2014)� Desert dust is a risk factor for the incidence of acute myocardial infarction in Western Japan� Circ Cardiovasc Qual Outcomes, 7, 743-8�
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