Characteristics of airborne asbestos concentrations in Korean preschools.
Once thought of as a wonder mineral because of its inherent beneficial qualities that included resistance to fire, heat, and corrosion--as well as being strong, durable, flexible, and inexpensive--asbestos has now become regarded as a hazardous material (International Agency for Research on Cancer [IARC] Working Group, 2012). Asbestos has been produced in Korea since the 1930s, and asbestos imports increased as secondary industries rapidly developed in the 1970s. These imports decreased from 1997 when some forms of asbestos, such as crocidolite and amosite, were prohibited (Park, Choi, Ryu, Park, & Paik, 2008). Then in 2009, after the Kubota Coincidence in Japan, use, manufacturing, distribution, and import of asbestos and asbestos-containing materials were prohibited in Korea (Kang & Kim, 2010; Kim, 2009). In Korea, asbestos mostly was used as materials for slates, car brake linings, fire-prevention dusting agents, pipe laggings, firefighting garments, electric appliance insulators, and floor tiles (Paik & Lee, 1991). In particular, approximately 80-95% of imported asbestos was used as building materials until the late 1990s (Jeong, Cho, Park, & Lee, 2013).
The hazards and dangers presented by exposure to asbestos, including chrysotile, cause an increased likelihood of developing cancer of the lung, larynx, and ovary; mesothelioma (a cancer of the pleural and peritoneal linings); and asbestosis (fibrosis of the lungs) (IARC, 2012).
Thus, Seoul is surveying the use of asbestos in city-owned public buildings and carrying forward a project to eliminate asbestos. It is also actively engaged in drawing a map of asbestos in asbestos-containing buildings (ACBs), and conducting promotional and education programs on asbestos management. Korea has included an item on asbestos in the Indoor Air Quality Control Act for public facilities such as libraries, museums, hospitals, preschools, passenger terminals, and subway stations. Asbestos in small-scale preschools smaller than 430 [m.sup.2], however, is not legally managed. Out of 43,646 preschools, 39,440 (90.4%) were small-scale preschools in Korea as of July 2014, which indicates that many preschools are excluded from asbestos management plans (Comprehensive Information Network for Asbestos Management, 2014). As a result of actually selecting and investigating 100 small-scale preschools smaller than 430 [m.sup.2] in the metropolitan area (Seoul, Incheon, and Kyeonggi), an area that accounts for half the population in our country, 8 out of the 29 schools (27%) in Seoul, 7 out of the 20 schools (35%) in Incheon, and 15 out of the 51 schools (29%) in Kyeonggi were identified, confirming that 30 (30%) out of the 100 small-scale preschools were made of asbestos-containing materials (Ministry of Health and Welfare [Korea], 2012).
Childcare for Korean children is heavily dependent on preschools as both parents are often engaged in economic activities. In addition, they want their children to receive quality education. Moreover, children spend most of their day in indoor spaces and are thereby susceptible to the indoor air quality; thus, parents prefer preschools with pleasant facilities and perceived better indoor air quality. There is no clear evidence indicating that children are more at risk than adults to asbestos exposure (Agency for Toxic Substances and Disease Registry, 2001). Children, though, can have a longer period of exposure to asbestos and therefore an earlier onset possibility of asbestos-related diseases.
Therefore, the objective of this study is to test the airborne asbestos concentrations in small-scale preschools built within ACBs in Seoul, and reduce the potential harm caused by asbestos by providing accurate information and an effective management plan.
Materials and Methods
Survey Period and Site
Samples were collected from a total of 91 points in 46 separate small-scale preschools at 20 boroughs in Seoul during 9 months, from April to December 2015, surveying airborne asbestos concentrations (Figure 1). Samples were collected from living spaces often encountered by children and teachers, as well as places where there might have been exposure to asbestos (Figure 2).
Sample Collection and Analysis
Sampling was conducted at locations within the indoor facilities. These locations were chosen to minimize changes in wind or airflow and the sampling was conducted by an air trapping method with an airflow rate of 10 L/ min to detect dust concentrations. In all, 1,210 L was sampled for 2 hours. A SARA-4000 Asbestos Sampler was used for the sampling of airborne asbestos in preschools. A mixed cellulose ester membrane filter (0.8 [micro]m pore size, 25 mm diameter) was used as the sampling filter. We measured samples in accordance with the indoor air quality standards of "Indoor air--How to measure the concentration of asbestos dust and fiber-phase microscopy" announced by Korea ES 02303.1 (Notice of Ministry of Environment No. 2010-24) (Ministry of Environment of Korea, 2010).
Samples were conducted in accordance with the aceton/triacetin method and then expressed as concentrations of fibrous materials (in f/cc) at a magnification of 400 times by phase contrast microscopy (PCM) inserted into the Walton-Beckett eyepiece graticule (Lange, 2001). Airborne fibrous materials were counted as fibrous (including asbestos) when the fibers had a length of >5 pm and a ratio of at least 3:1 in diameter.
When the result of analyzing with PCM exceeded 0.01 f/cc (the Indoor Air Quality Control Act criterion), we prepared the remaining samples without an additional sample collection, and analyzed them with transmission electron microscopy (TEM) according to the ISO 10312 method (International Organization for Standardization [ISO], 1995).
Samples were analyzed at 18,500x magnification, which were counted as asbestos f/cc according to the ISO 10312 rule (ISO, 1995), while asbestos structures/cc (s/cc) were counted according to the Asbestos Hazard Emergency Response Act (AHERA) rule (U.S. Environmental Protection Agency, 1987). Airborne asbestos concentrations of small-scale preschools were examined by determining whether the airborne fibrous materials from the PCM analysis results were actual asbestos fibers.
Management of Asbestos in SmallScale Preschools
We selected 46 small-scale preschools in Seoul, collected samples from 91 points, and analyzed them with PCM and TEM. We found that for ACB materials in preschools, textiles accounted for at least 80% of the asbestos materials, and the remaining 20% was made up of baumlite and slate. Of the 46 preschools, 44 of them were being managed in a satisfactory condition, while two were likely to reveal the presence of airborne asbestos; 34 of them had indoor wallpapers or paint on the walls (Table 1).
Airborne Fibrous Materials With PCM
PCM test results showed that four (classroom, bathroom, lounge, corridor) out of the seven spaces or rooms monitored had average concentrations of fibrous materials at 0.01 f/cc or above, which is the Indoor Air Quality Control Act criterion (Ministry of Environment of Korea, 2017). Overall, the distribution was 0.000-0.040 f/cc (Table 2, Figure 3). Of the total 91 points, 29 points exceeded 0.010 f/cc, but we used TEM for a precise analysis, as the measured fibrous materials cannot be assumed to be asbestos.
Airborne Fibrous Materials With TEM
As a result of analysis with sensitivity 0.0009 f/cc according to the ISO 10312 method (length > 5 [micro]m, width 0.2-3.0 [micro]m, lengthto-width ratio [greater than or equal to] 3:1) using TEM, 0.0018 f/cc (teachers room) of chrysotile was detected from one preschool, but it still complied with the Indoor Air Quality Control Act ([greater than or equal to] 0.01 f/cc), while chrysotile was not detected in any of the other preschools. As a result of analysis with sensitivity 0.0036 s/cc according to the AHERA method (length [greater than or equal to] 0.5 [micro]m, width > 0.25 [micro]m, length-to-width ratio [greater than or equal to] 5:1), 0.0072 s/cc (teachers room) and 0.0036 s/cc (classroom) of chrysotile were detected in two preschools. These numbers are lower than the filter background level. Chrysotile, however, was not detected in any of the other preschools (Figure 4).
On the other hand, even though it was expected that airborne asbestos would be detected in the two preschools that contain it, surprisingly, airborne asbestos was not detected in these two schools. By construction year, 39 out of the 46 preschools (85%) were constructed in the 1980s and 1990s, and asbestos was detected in one preschool constructed in the 1980s and one preschool constructed in the 1990s by applying the AHERA method (length [greater than or equal to] 0.5 [micro]m, width > 0.25 [micro]m, length-to-width ratio [greater than or equal to] 5:1) (Table 3).
We examined asbestos concentrations obtained at 91 points from 46 small-scale preschools that were smaller than 430 [m.sup.2] in Seoul, and they all complied with the Indoor Air Quality Control Act ([greater than or equal to] 0.01 f/cc). Any particle longer than 5 [micro]m in length shall be defined as an asbestos fiber according to Korean law. A particle of the minimum length of 0.5 [micro]m, however, is defined as asbestos fiber in the U.S. (AHERA method), so we sought to detect and identify the distribution of fibers that were less than 0.5 [micro]m.
Chrysotile was found in two preschools, in a teachers room and a classroom, at lower than the filter background level. The principal varieties of asbestos are a serpentine material called chrysotile, and crocidolite, amosite, anthophyllite, tremolite, and actinolite--which are a type of dark mineral called amphiboles (Mirabelli et al., 2008). All detected asbestos was chrysotile, which was less than 10 pm long. Chrysotile, if smaller than 20 pm, generally can be broken down in the body, but other amphiboles are deposited on the diaphragm, causing fibrosis (Bernstein et al., 2013).
All detected chrysotile was less than 10 pm, and thus presented a low risk. Asbestos was barely detected in small-scale preschools smaller than 430 [m.sup.2] in Seoul, even though they are ACBs. This finding is because most preschools naturally prevented airborne asbestos by using wallpapers, paints, and silicon finishes in the interior for heat insulation. By construction year, the preschools constructed in the 1980s and 1990s accounted for the highest percentage, and one of the preschools where asbestos was detected was a preschool located in the Gangnam borough, which is an economically advantaged area in Seoul.
Korea has prohibited the use of asbestos since 2009, and thus new buildings are made of non-asbestos materials. The problem is that many preschools built before 2009 are ACBs, and therefore present a real risk of exposure to asbestos for inhabitants-a risk which must be managed.
In general, there are two ways to reduce the risk from asbestos.
1) Dismantle and remove the asbestos. Asbestos is likely to be emitted in the process of dismantling it, and the need for containment will also generate costs. When dismantling asbestos buildings, it is necessary to establish a systematic plan and methods to prevent airborne asbestos.
2) Maintain and manage the buildings by establishing prevention methods (enclosure, encapsulation, repair). Airborne asbestos can be managed safely by preventing damage to ceiling textiles and paint on walls and ceilings, by using wallpapers and gap-filling materials, and by applying stabilizers. There was also a report in the U.S. that asbestos concentrations are not high in buildings on a daily basis, and thus it is appropriate that the risk be managed instead of removing the asbestos (Lee & Van Orden, 2008). Asbestos was barely detected in this study, confirming that the asbestos exposure levels are not high in preschools on a daily basis.
The risk posed by asbestos is emerging as a major social issue in Korea. This issue is only natural considering the fact that asbestos is a carcinogen that was commonly used in Korea and also that there is greater interest in and awareness of matters related to health and safety. Excessive concerns over the risk of exposure to asbestos, however, may create social fear and confusion. Countries such as the U.S. assume, in the managerial sense, that asbestos poses little risk as long as it is not emitted in the air, and management plans are established accordingly. Therefore, it is desirable for Korea also to establish maintenance plans in consideration of the potential for airborne asbestos, as well as the costs associated with managing the risk (Yoon, 2009).
The metropolitan government in Seoul is continuing to remove asbestos in multiuse buildings owned by the city year by year. This action is taken out of consideration for the health of citizens, as many citizens use such buildings. Considering the fact that most small-scale preschools are private properties where asbestos is rarely detected, it is desirable to implement strict preventive measures and perform regular monitoring. We believe that it is possible to be safe from asbestos as long as we properly maintain and manage the buildings containing asbestos, like the small-scale preschools in this study. In other words, despite the harmfulness of asbestos, the risks can be reduced by effective maintenance to prevent airborne emission.
Young children in the process of physical development have weaker immune systems and are more sensitive to pollutants than adults--thus it is important to establish measures to prevent airborne asbestos in preschools that were built with materials containing asbestos. In particular, even though small-scale preschools smaller than 430 [m.sup.2] account for 90.4% of preschools in Korea, there are no legal standards for the detection, control, and management of asbestos in such places. This study examined airborne asbestos concentrations in small-scale preschools and discovered that the asbestos levels met national standards, even though a small amount of chrysotile was detected in a few of the preschools. Most preschools were preventing exposure to asbestos because walls and ceilings were covered with wallpapers and paints. Therefore, the most appropriate method is to regularly monitor asbestos, develop and apply effective measures and technology to prevent airborne asbestos, and minimize exposure to asbestos until it is removed.
Institute of Public Health and Environment
Seoul Metropolitan Government Research
Department of Public Health
Institute of Public Health and Environment
Seoul Metropolitan Government Research
Acknowledgement: The authors would like to thank director Seokju Cho; Miok Song, PhD; and Jinhyo Lee, PhD, from the Seoul Institute of Health and Environment for providing invaluable advice and input.
Corresponding Author: Changkyu Kim, Particle Research Team, Institute of Public Health and Environment, Seoul Metropolitan Government Research, 202-3, Yangjae-dong, Seocho-gu, Seoul, Korea, 137-130.
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Caption: FIGURE 1 Sampling Sites of Small-Scale Preschools at 20 Boroughs in Seoul, Korea
Caption: FIGURE 3 Distribution of the Airborne Concentrations of Fibrous Materials Detected With Phase Contrast Microscopy
Caption: FIGURE 4 Transmission Electron Microscopy Image of Chrysotile in a Preschool
TABLE 1 Management State of Asbestos Materials in Small-Scale Preschools Condition Satisfactory Damaged 44 2 Asbestos-Containing Materials Textile Textile and Baumlite Slate Baumlite 27 10 7 2 Interior Wallpaper Paint on the Others Walls 27 7 15 Note. The damage level, types of asbestos-containing materials, and interior status were examined by on-site visits to the preschools. TABLE 2 Concentrations of Airborne Fibrous Materials Detected With Phase Contrast Microscopy Analysis Places # of Maximum Minimum Samples (f/cc) (f/cc) Teachers room 13 3 0.035 0.000 Classroom 41 16 0.031 0.002 Bathroom 7 3 0.026 0.006 Lounge 3 2 0.022 0.004 Kitchen 3 0 0.003 0.002 Corridor 3 1 0.011 0.009 Others 21 4 0.040 0.000 Total 91 29 0.040 0.000 Places Mean [+ or -] SD Criteria (f/cc) Teachers room 0.009 [+ or -] 0.010 Indoor Air Quality Classroom 0.010 [+ or -] 0.008 Control Act ([less Bathroom 0.012 [+ or -] 0.007 than or equal to] Lounge 0.013 [+ or -] 0.009 0.01 f/cc) Kitchen 0.003 [+ or -] 0.001 Corridor 0.010 [+ or -] 0.001 Others 0.007 [+ or -] 0.008 Total 0.009 [+ or -] 0.008 Note. The concentration (f/cc) is determined by counting only fibers with length > 5 [micro]m and a length-to-width ratio of [greater than or equal to] 3:1. (a) The number of places in which concentrations of airborne fibrous materials exceeds 0.010 f/cc. TABLE 3 Distribution of Airborne Asbestos in Preschools by Construction Year Detected With Transmission Electron Microscopy Construction Year Preschool Airborne Asbestos Detected at Preschool [less than or equal to] 1980 2 0 1981-1990 13 1 1991-2000 26 1 [greater than or equal to] 2000 5 0 Total 46 2 Construction Year Transmission Electron Microscopy [less than or equal to] 1980 ND 1981-1990 0.0072 s/cc (Guro borough) 1991-2000 0.0036 s/cc (Gangnam borough) [greater than or equal to] 2000 ND Total -- ND = not detected. Note. Asbestos was detected by applying the Asbestos Hazard Emergency Response Act method (length [greater than or equal to] 0.5 [micro]m, width > 0.25 [micro]m, and a length-to-width ratio [greater than or equal to] 5:1). FIGURE 2 Sampling Points in Small-Scale Preschools Teachers Room 14% Corridor 3% Kitchen 3% Lounge 4% Classroom 45% Bahtroom 8% Others 23% Note: Table made from pie chart.
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|Title Annotation:||INTERNATIONAL PERSPECTIVES|
|Author:||Ha, Kwangtae; Chung, Sooknye; Lee, Suhyun; Kang, Mihae; Kim, Gayeon; Yoo, Seungsung; Eo, Soomi; Jung|
|Publication:||Journal of Environmental Health|
|Date:||Jul 1, 2017|
|Previous Article:||Professional (dis) association.|