ABSTRACT
The Republic of Korea (ROK) is a country in the southern part of the Korean peninsula, which stretches south from the northeast coast of Asia� It shares oversea borders with China to the west and Japan to the east� The size of land is 99,392 km2, and the number of residents is approximately 50 million, including approximately 10 million people in Seoul, the capital� There are six metropolitan cities (Incheon, Daejeon, Daegu, Ulsan, Gwangju, and Busan), and each city has over 1 million residents�
The ROK is located in the midlatitude temperate climate zone (33°–43° north latitude, 124°–132° east longitude) with a humid continental and subtropical climate, and the spring, summer, autumn, and winter seasons are distinct� Except in the mountains and islands, the annual average temperature is 10°C-15°C, and the monthly
6�1 Background ��������������������������������������������������������������������������������������������������� 115 6�1�1 Demographics of the Republic of Korea ������������������������������������������ 115 6�1�2 Economic Growth and Increase in Traffic and Air Pollution ����������� 116
6�2 Health Effects ����������������������������������������������������������������������������������������������� 116 6�2�1 Mortality ������������������������������������������������������������������������������������������� 116 6�2�2 Respiratory System ��������������������������������������������������������������������������� 117 6�2�3 Cardiovascular System ��������������������������������������������������������������������� 119 6�2�4 Reproductive System ������������������������������������������������������������������������ 120
6�3 Exposures ������������������������������������������������������������������������������������������������������ 121 6�3�1 Air Pollution Monitoring Network ��������������������������������������������������� 121 6�3�2 Current Status of Air Pollution ��������������������������������������������������������� 123
6�4 Risk Assessment and Management �������������������������������������������������������������� 127 6�4�1 Air Emissions ����������������������������������������������������������������������������������� 127 6�4�2 Air Policy Overview ������������������������������������������������������������������������� 129 6�4�3 Protecting Public Health from Environmental Risks ����������������������� 130
6�5 Conclusion ���������������������������������������������������������������������������������������������������� 132 References �������������������������������������������������������������������������������������������������������������� 132
average ranges from −6°C to 3°C in January to 23°C-26°C in August� Throughout the year, the amount of rainfall is 1200-1500 mm in the Northern provinces and 1000-1800 mm in the Southern provinces� Seasonally, 50%–60% of the annual precipitation occurs in summer� The relative humidity is 60%–75% throughout the year, 70%–85% in July and August, and 50%–70% in March and April�
The ROK has experienced dramatically accelerated urbanization resulting from rapid economic development and increased industrialization� From 1960 to 1990, the population increased by nearly 17 million, and the gross domestic product (GDP) increased more than 130 times during the same period, from 200 million dollars to 263�7 billion dollars (Korea National Statistical Office, 2008)� During the same period, the population in urban areas was only 27�7% in 1960 but increased to 73�8% in 1990 (United Nations, 2012)�
In terms of energy use, the ROK used to mostly depend on coal and wood for fuel in the 1960s, but oil has become the largest energy source since the 1970s� In the 1980s, the government adopted air pollution reduction policies including the supply of low-sulfur fuel, lead-free fuel, and liquefied petroleum gas, which might contribute to a decrease in the levels of several major air pollutants such as sulfur dioxide (SO2), carbon monoxide (CO), and lead (Kim, 2013)� However, there has been a drastic increase in the number of vehicles from 130,000 in 1970 to 12�1 million in 2000 (Korea National Statistical Office, 2008), and traffic-related air pollution has been an issue in urban areas�
Recently, China has been experiencing extremely rapid economic development that has imposed significant pressure on the environment (Asia Pacific Energy Research Centre, 2004)� Air pollutants emitted in China and carried by the westerly winds appeared to contribute to 20%–40% of sulfur oxides (SOx) (National Institute of Environmental Research [NIER], 2009) and up to 65% of nitrogen oxides (NOx) (NIER, 2012) in the ROK� Furthermore, because meteorological factors are related to the generation of secondary pollutants such as O3, the influence of climate change on air pollutants cannot be ignored� Therefore, although the ROK has endeavored to improve air quality for several decades, air pollution still remains problematic and deserves more attention�
The association of air pollution with mortality in the ROK has been investigated since the late 1990s, focusing on acute effects through time-series or time-stratified case-crossover studies� A study of the former type suggested that an increase of 100 μg/m3 in total suspended particulates (TSP) was related to a 3% increase in daily mortality in Ulsan, an industrialized city, from 1991 to 1994 (Lee et al�, 1998)� Kwon and Cho (1999) found that the risk of daily mortality due to air pollution increased
in Seoul from 1991 to 1995� They showed that air pollutants such as O3, nitrogen dioxide, TSP, and SO2 were associated with the risk of mortality, and a remarkable association was shown for O3 (6% change; 95% confidence interval [CI], 2%–10% per 100 ppb)�
In 1994, the Ministry of Environment started to monitor, in addition to TSP, particulate matter ≤10 μm in aerodynamic diameter (PM10), and since then, researchers have reported an association between PM10 and daily mortality� We analyzed death statistics and air pollution data from an automatic monitoring system (19992008) in Seoul with a time-stratified case-crossover study design (Shin, 2010)� The increased risks for all-cause mortality related to PM10 were statistically significant in the cumulative lag2 model, averaging concentrations from the same day to the subsequent 2 days before death (odds ratio [OR], 1�005; 95% CI, 1�003-1�007 per 22 μg/m3)� Regarding cause-specific mortality, both cardiovascular and cerebrovascular deaths were significantly associated with PM10 exposure in the cumulative lag2 models� The highest risks were observed in the cumulative lag1 model for deaths from myocardial infarction (OR, 1�011; 95% CI, 1�001-1�021)� Ha et al� (2011) conducted a further study in the same manner, expanded to seven major cities (Seoul, Incheon, Daejeon, Daegu, Ulsan, Gwangju, and Busan)� They analyzed deaths of people ≥40 years old (n = 160,273) from 2002 to 2008, and the results from each city were combined using a random-effects meta-regression model� An interquartile range (IQR) (39�05 μg/m3) increase in PM10 was associated with the risk of death from cardiovascular and cerebrovascular disease (0�8% change; 95% CI, 0�1%–1�6%)�
Ample evidence has informed us about the relationships between air pollution and mortality, but in terms of public health implications, it is imperative to identify for whom and when the risk is higher for death due to air pollution� The study of Ha et al� (2011) also analyzed the data after stratification by age (40-64 and ≥65 years of age) and found a significant risk for cardiovascular and cerebrovascular mortality only in the elderly� Another study using the data from 2000 to 2006 in Seoul also showed a significantly increased risk for all-cause mortality in the ≥66-year-old group, but the increased risk was not significant in the <66-year-old group (Yi et al�, 2010)� These results underscore the need to treat the elderly as susceptible to the effects of air pollution� In addition, Yi et al� (2010) focused on a seasonal effect in the association between PM10 concentrations and mortality, suggesting significantly increased risks for nonaccidental mortality in summer and for cardiovascular mortality in autumn� To explain this seasonal difference, they suggested that individual behaviors related to exposure to air pollutants might affect the seasonality of the association�
There has been a long-standing concern about the health effects of air pollution on the respiratory system� In the 1960s, the first study in Korea reported that daily visits of patients were associated with ambient SO2 and CO concentration in Seoul (Chung, 1969)� In the 2000s, with more information on air pollutants, epidemiologic studies
on the effects of air pollution on the respiratory system have primarily focused on acute effects using medical care utilization and pulmonary function data� A panel study assessed the influence of PM10 on normal children’s lung function (Kim et al�, 2005)� The researchers found that the forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were lower in relatively high PM10 conditions� Another study found that O3 was associated with lung function using interpolation methods (Son et al�, 2010)� An 11 ppb increase in O3 was associated with a 6�1% (95% CI, 5�0%–7�3%) decrease in FVC and a 0�50% (95% CI, 0�03%–0�96%) decrease in FEV1�
Among respiratory diseases, asthma has been of main interest, especially in children� Lee et al� (2002) analyzed daily admission for asthma, using the Medical Insurance Corporation’s reports from all hospitals of only patients younger than 15 years of age who lived in Seoul from 1997 to 1999� They conducted a time-series study of 6436 asthma-related hospital admissions� The relative risk (RR) of hospitalization for asthma was 1�07 (95% CI, 1�04-1�11) for PM10 (IQR, 40�4 µg/m3); SO2, nitrogen dioxide (NO2), O3, and CO were also associated with hospitalization for asthma� The importance of identifying a susceptible group was also highlighted in a study of Park et al� (2013), who conducted a time-series study from 1999 to 2003 in seven metropolitan cities� Using 15-to 64-year-old subjects as the reference, the relative rate of asthma admissions with a 10 μg/m3 increase of PM10 is 1�5% (95% CI, 0�1%–2�8%) lower for children and 1�3% (95% CI, 0�7%–1�9%) higher for the elderly; the relative rate with a 1 ppm increase of CO is 1�9% (95% CI, 0�3%–3�8%) lower for children; and the relative rate with a 1 ppb increase of NO2 (1 ppb) is 0�5% (95% CI, 0�3%–0�7%) higher for the elderly� Recently, our group conducted a time-series study to evaluate the risk of emergency department (ED) visits for asthma exacerbation related to air pollutants� The study evaluated ED visits from 2005 to 2009 in Seoul� During the study period, 27,896 asthma attack cases were observed� The risk of an ED visit for an asthma attack increased by 5�3% (95% CI, 3�7%–7�0%) with an increase of O3 (standard deviation, 0�01 ppm) on the same day�
Using biological monitoring data, Kim et al� (2005) suggested a relationship of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) with the occurrence of asthma in children� They assessed their exposure levels to VOCs by measuring urinary concentrations of hippuric acid and muconic acid (for VOCs) and 1-OH-pyrene and 2-naphthol (for PAHs) in 30 children with asthma (cases) and 30 children without asthma (controls)� The mean concentration of muconic acid and the mean level of urinary 1-OH-pyrene were higher in the asthma group than in the control group� They suggested that VOCs and PAHs have some role in asthma�
Another group focused on relationship between long-term exposure and lung cancer� Using random-intercept Poisson regression and an empirical Bayesian method, they calculated the standardized incidence ratio and standardized mortality ratio� The estimated percent increases in the rate of female lung cancer incidence and mortality were 65% and 27%, respectively, at the highest PM10 category (≥70 μg/m3) compared with the reference category (<50 μg/m3)�
Despite a high economic status of the ROK, tuberculosis (TB) remains an important health problem in the country� According to a retrospective cohort study of the population of Seoul (Hwang et al�, 2014), from 2002 to 2006, 41,185 TB cases were
reported to the Korean Institute of Tuberculosis� An IQR increase (0�3 ppb) in outdoor SO2 concentration was associated with a 7% increase in TB incidence (RR, 1�07; 95% CI, 1�03-1�12)�
Based on these studies, we can conclude that air pollution affects the health of the respiratory system� Air pollution is related to decreases in lung function, asthma and its exacerbation, lung cancer, and even TB�
There is increasing evidence about the adverse cardiovascular or cerebrovascular effects of air pollution in Korea� Several epidemiologic studies have shown the potential outcomes, including increased daily mortality, hospital admissions, and heart-rate variability (HRV)�
An early study was conducted about susceptibility in patients with congestive heart failure mediated by cardiovascular mechanisms (Kwon et al�, 2001)� The effect of air pollution on daily mortality of two study populations, a general population and congestive heart failure patients among residents of Seoul, was analyzed by general additive Poisson regression in a case-crossover study from 1994 to 1998� The estimated effects appeared larger among the congestive heart failure patients than among the general population (approximately 2�5-4�1 times higher depending on the pollutants)� The finding that patients with congestive heart failure were more susceptible to air pollution strengthens the evidence that an important mechanism of the air pollution effect involves the cardiovascular system�
Another study also reported the effects of ambient air pollution on hospital admissions for ischemic cardiovascular diseases within an elderly population in Seoul (Lee et al�, 2003)� The RRs of hospitalization associated with an IQR increase in pollution concentrations were estimated by using a generalized additive Poisson model in a time-series analysis� The estimated effects of hospitalization were 1�05 (95% CI, 1�01-1�10) for PM10, 1�10 (95% CI, 1�05-1�15) for O3, 1�08 (95% CI, 1�03-1�14) for NO2, and 1�07 (95% CI, 1�01-1�13) for CO� The finding that hospital admission for ischemic heart diseases was associated significantly with ambient air pollutants may provide the insights that the elderly appear to be at particular risk from the effects of air pollution, at pollutant levels lower than the standards adopted by most governments�
Min et al� (2008) studied the effects of ambient air pollutants on cardiac autonomic function by measuring HRV in 1349 community residents in Korea (596 men and 753 women)� Linear regression analyses were carried out to evaluate the association over 72 hours, and the parameters of HRV indices were presented as the percent change� The findings that the exposures to PM10, SO2, and NO2 were significantly associated with reduced HRV indices suggest that air pollutants stimulate the autonomic nervous system, provoke an imbalance in cardiac autonomic control, and may lead to pathological consequences particularly in high-risk patients and susceptible subjects�
Similarly, a few studies were also conducted to assess the association between ambient air pollution and cerebrovascular disease such as acute stroke� Hong et al� (2002) investigated the association between acute stroke mortality and air pollution
over a 7-year period from 1991 to 1997 in Seoul� A time-series analysis with a generalized additive model was used to examine the effects of air pollutants on ischemic and hemorrhagic stroke deaths, and significantly increased RRs were found for ischemic stroke mortality for TSP and SO2� However, as dramatic improvements in the treatment for acute fatal strokes have resulted in a decrement in stroke mortality, it is now much more important to consider the incidence of stroke to evaluate the disease burden of acute stroke�
More recently, our group conducted another study to examine the short-term effect of ambient air pollutants on the incidence of acute stroke� A time-series design using generalized additive models with Poisson regression was applied to evaluate ED visits in Seoul from 2005 to 2009� The RRs of emergency visits for stroke were 1�016 (95% CI, 1�011-1�023) per 12�04 ppb increment of NO2 and 1�014 (95% CI, 1�007-1�020) per 0�24 ppm increment of CO, and our results suggest that ambient air pollution increases the risk of cardiovascular and cerebrovascular disease in Korea�
Air pollution contributes to the consistent increased risk for cardiovascular or cerebrovascular events in relation to both short-and long-term exposure by several plausible pathways� Oxidative stress as a critically important cause and consequence of PM-mediated cardiovascular effects has a sound experimental basis, and some of the general pathways including systemic inflammation, autonomic nervous system imbalance, and PM or its constituents reaching the systemic circulation can be capable of eliciting cardiovascular events (Brook et al�, 2010)� Recently, our group investigated the arrhythmogenic mechanism of PM via oxidative stress and calcium calmodulin kinase II activation that might help to explain the relationship between air pollution and increased arrhythmia (Kim et al�, 2012)� Nevertheless, there is not enough research on air pollution and cardiovascular diseases in Korea, and more investigations are required because the underlying mechanisms involved are not yet fully understood�
Neonates, infants, and children are considered susceptible to air pollution because their respiratory and immune systems are immature (Braga et al�, 2001)� During pregnancy, gaseous pollutants such as CO can be transmitted to the fetus via the placenta (Longo, 1977), and systemic inflammation induced by particulates might increase blood viscosity (Peters et al�, 1997)� Collectively, these mechanisms can lead to low oxygen delivery in the fetus and consequently low birth weight and infant mortality�
In the ROK, the relationship between air pollution and reproductive outcomes was first explored by Ha et al� (2001), who hypothesized that air pollution exposure during pregnancy is associated with low birth weight in full-term births� In generalized additive logistic regression models, CO, NO2, SO2, and TSP exposure in the first trimester of pregnancy increased the risk for low birth weight� This research group conducted a further study to find a specific month of pregnancy during which exposure resulted in a high risk for low birth weight (Lee et al�, 2003)� They suggested that low birth weight was associated with CO, NO2, SO2, and PM10 exposure in months 2-5, 3-5, 3-5, and 2-4 during pregnancy, respectively�
Another stream of research on reproductive outcome examines infant mortality� To investigate the acute effect, Ha et al� (2003) compared mortality among infants, a 2-to 64-year-old group, and a ≥65-year-old group� Among all age groups, infants were at the highest risk for all-cause mortality (RR, 1�142; 95% CI, 1�096-1�190; per 42�9 μg/m3) and respiratory mortality (RR, 2�018; 95% CI, 1�784-2�283; per 42�9 μg/m3) related to PM10 exposure� In terms of a long-term effect, a study focused on infant mortality due to gestational and lifetime exposure to particulate matter using survival analysis (Son et al�, 2011)� The authors found positive associations of gestational exposure to particulate matter with all-cause and respiratory mortality in infants�
The national air pollution monitoring network examines the status of the ambient air pollution nationwide and contributes to the advancement of air quality control policies in the ROK (Table 6�1)� The national air pollution monitoring network provides information on air pollution to the public via the National Ambient Air Monitoring System (NAMIS), and the Airkorea (Real-time Ambient Air Quality Monitoring System)� The NAMIS system collects, selects, and creates the statistics on the data monitored by the ambient air monitoring network nationwide and provides these data to administrative organizations on a government-and a self-governing level� It shares the information on the ambient pollution and utilizes it as the basic data to set the ambient air conservation
TABLE 6.1 Types of Ambient Air Monitoring Networks in Korea (Based on December 2012 Data)
TABLE 6.1 (Continued ) Types of Ambient Air Monitoring Networks in Korea (Based on December 2012 Data)
policy� The data and information on the ambient air pollution gathered by the ambient air quality monitoring network are provided in real time on the Airkorea website for the public� Airkorea describes ambient air quality based on the health risk of air pollution (Korea Environment Corporation, 2012; Airkorea, 2012)�
During the last 10 years in the ROK, the annual averages of SO2, CO, and NO2 concentrations in ambient air were approximately 0�05, 0�1, and 0�02 ppm, respectively (Figure 6�1)� Lead is in a declining trend with an annual level of 0�05� In contrast, the annual average of O3 concentration was 0�025 ppm in 2012 and slightly rising every year (Korea NIER, 2013)� Especially, the PM10 concentration in the Seoul metropolitan area in the early 2000s was high, at approximately 70 μg/m3 (Figure 6�2)�
In order to protect the health of Korean citizens, the Korean government established and promoted a basic plan for air quality management of the capital area, such as installation of emission reduction devices on diesel engine vehicles and low-pollution vehicle supply projects (393,837 vehicles), total air pollution load management systems at places of business (304 places), and low NOx burner installation projects (2931 vehicles)� In the meantime, the PM10 concentration has been improving every year; the PM10 concentration in the capital area was reduced
TABLE 6.1 (Continued ) Types of Ambient Air Monitoring Networks in Korea (Based on December 2012 Data)
FI G
U R
E 6.
