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Characteristics of airborne asbestos concentrations in Korean preschools.

Introduction

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

Method

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.

Results

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).

Discussion

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.

Conclusion

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.

Kwangtae Ha

Sooknye Chung

Suhyun Lee

Mihae Kang

Institute of Public Health and Environment

Seoul Metropolitan Government Research

Gayeon Kim

Department of Public Health

Dankook University

Seungsung Yoo

Soomi Eo

Kweon Jung

Changkyu Kim

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.

E-mail: ckkim0707@seoul.go.kr.

References

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Bernstein, D., Dunnigan, J., Hesterberg, T., Brown, R., Velasco, J.A., Barrera, R., ... Gibbs, A. (2013). Health risk of chrysotile revisited. Critical Reviews in Toxicology, 43(2), 154-183.

Comprehensive Information Network for Asbestos Management. (2014). The number of preschools in Korea. The Ministry of Environment [Website in Korean]. Retrieved from http://asbestos. me.go.kr/user/gc/asbStaStrPstCdt_new.do

International Agency for Research on Cancer Working Group on the Evaluation of Carcinogenic Risk to Humans. (2012). Asbestos (chrysotile, amosite, crocidolite, tremolite, actinolite and anthophyllite). In Arsenic, metals, fibres and dusts. Lyon, France: International Agency for Research on Cancer (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, No. 100C). Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK304374

International Organization for Standardization. (1995). Ambient air--Determination of asbestos fibres-Direct transfer transmission electron microscopy method (ISO 10312:1995). Retrieved from http://www.iso.org/iso/catalogue_detail.htm7csnum ber=18358

Jeong, J.-W., Cho, S., Park, G.-T., & Lee, S.-J. (2013). Health risk assessment and evaluation of asbestos release from asbestoscement slate roofing buildings in Busan. Journal of Environmental Science International, 22(12), 1579-1587.

Kang, S.-K., & Kim, E.A. (2010). Occupational diseases in Korea. Journal of Korean Medical Science, 25(Suppl), S4-S12.

Kim, H.R. (2009). Overview of asbestos issues in Korea. Journal of Korean Medical Science, 24(3), 363-367.

Lange, J.H. (2001). Airborne asbestos concentrations during abatement of floor tile and mastic: Evaluation of two different containment systems and discussion of regulatory issues. Indoor and Built Environment, 10(3-4), 193-199.

Lee, R.J., & Van Orden, D.R. (2008). Airborne asbestos in buildings. Regulatory Toxicology and Pharmacology, 50(2), 218-225.

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Ministry of Health and Welfare (Korea). (2012). Asbestos survey on child care center and development of asbestos management standard model (page 1).

Mirabelli, D., Calisti, R., Barone-Adesi, F., Fornero, E., Merletti, F, & Magnani, C. (2008). Excess of mesotheliomas after exposure to chrysotile in Balangero, Italy. Occupational and Environmental Medicine, 65(12), 815-819.

Paik, N.W., & Lee, Y.H. (1991). Characterization of worker exposure to airborne asbestos in asbestos industry. Journal of Korean Society of Occupational and Environmental Hygiene, 1(2), 144-153.

Park, D., Choi, S., Ryu, K., Park, J., & Paik, N. (2008). Trends in occupational asbestos exposure and asbestos consumption over recent decades in Korea. International Journal of Occupational and Environmental Health, 14(1), 18-24.

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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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Article Details
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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
Article Type:Report
Geographic Code:9SOUT
Date:Jul 1, 2017
Words:3410
Previous Article:Professional (dis) association.
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