Indoor air quality differences between urban and rural preschools in Korea

Our plain-English summary of Indoor air quality differences between urban and rural preschools in Korea, by C. Yoon, K. Lee, D. Park (Environmental Science and Pollution Research International, 2011).

The study

• Authors: C. Yoon, K. Lee, D. Park
• Journal: Environmental Science and Pollution Research International
• Published: 2011;18(3):333-45
• Cited by: 56 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background, Aims, And Scope: Preschool indoor air quality (IAQ) is believed to be different from elementary school or higher school IAQ and preschool is the first place for social activity. Younger children are more susceptible than higher-grade children and spend more time indoors. The purpose of this study was to compare the indoor air quality by investigating the concentrations of airborne particulates and gaseous materials at preschools in urban and rural locations in Korea.

Methods: We investigated the concentrations of airborne particulates and gaseous materials in 71 classrooms at 17 Korean preschools. For comparison, outdoor air was sampled simultaneously with indoor air samples. Airborne concentrations of total suspended particulates, respirable particulates, lead, asbestos, total volatile organic compounds and components, formaldehyde, and CO(2) were measured with National Institute for Occupational Safety and Health and/or Environmental Protection Agency analytical methods.

Results: The concentration profiles of the investigated pollutants in indoor and urban settings were higher than those in outdoor and rural areas, respectively. The ratios of indoor/outdoor concentrations (I/O) of particulates and gaseous pollutants were characterized in urban and rural preschools. Total dust concentration was highest in urban indoor settings followed by urban outdoor, rural indoor, and rural outdoor locations with an I/O ratio of 1.37 in urban and 1.35 in rural areas. Although I/O ratios of lead were close to 1, lead concentrations were much higher in urban than in rural areas. The I/O ratio of total VOCs was 2.29 in urban and 2.52 in rural areas, with the highest level in urban indoor settings. The I/O ratio of formaldehyde concentrations was higher in rural than in urban areas because the outdoor rural level was much lower than the urban concentration. Since an I/O ratio higher than 1 implies the presence of indoor sources, we concluded that there are many indoor sources in preschools.

Conclusions: We confirmed that pollutants in indoor and urban settings were higher than those in outdoor and rural areas, respectively. Preschool children are expected to spend more time inside preschool facilities and therefore to be more exposed to pollutants. As far as we know, preschool IAQ is different from elementary school or higher school IAQ. Also, they are more vulnerable than higher-grade children. We found that the indoor and urban concentration profiles of the studied pollutants in preschools were higher than those in outdoor and rural areas. We believe that our findings may be useful for understanding the potential health effects of exposure and intervention studies in preschools.

In plain English

This study measured indoor and outdoor air pollutants at 17 Korean preschools (13 urban, 4 rural). These had agreed to take part out of 100 randomly selected. In total, 71 of 91 classrooms were sampled. Pollutants measured included dust, lead, airborne fibers, volatile organic compounds, formaldehyde and carbon dioxide. Fibers were counted by phase contrast microscopy. The authors said this method may overestimate asbestos because it cannot reliably separate asbestos from other fibers. Eleven of 54 urban classroom samples (20.4%) and 1 of 17 rural ones (5.9%) exceeded the US EPA guideline of 0.01 fibers per cubic centimeter. Outdoor samples were below or near the detection limit. Average indoor fiber levels were 0.006 f/cc in urban and 0.003 f/cc in rural classrooms. Of 20 suspect building materials, five ceiling boards contained 1 to 3% chrysotile. Fiber levels in schools with and without such materials did not differ significantly. All measured pollutants except benzene in rural areas were higher indoors than outdoors. The authors concluded that preschools have many indoor pollutant sources. They noted possible selection bias and that sampling covered only late spring and summer, not winter.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Cross-sectional environmental measurement study comparing indoor and outdoor air at urban and rural preschools
• Who was studied: 17 Korean preschools (13 urban, 4 rural) that consented out of 100 randomly selected; 71 of 91 classrooms measured, with outdoor samples taken at the same time; sampling in late June and early September
• Exposure: Airborne total and respirable dust, lead (air and surface wipes), airborne fibers counted by phase contrast microscopy (NIOSH 7400), bulk samples of suspected asbestos-containing materials examined by polarized light microscopy, total and individual volatile organic compounds, formaldehyde, carbon dioxide and carbon monoxide
• Main results:
  • 11 of 54 urban classroom samples (20.4%) and 1 of 17 rural indoor samples (5.9%) exceeded the US EPA guideline of 0.01 fibers per cubic centimeter
  • All outdoor fiber samples were below or near the detection limit of 0.001 f/cc
  • Indoor fiber concentrations were higher in urban classrooms (0.006, SD 0.006 f/cc) than in rural classrooms (0.003, SD 0.003 f/cc; p=0.02)
  • Of 20 suspected asbestos-containing materials, five bulk samples (25%), all ceiling boards, contained 1 to 3% chrysotile
  • Airborne fiber levels did not differ significantly between schools with and without asbestos-containing materials (0.006, SD 0.005 vs 0.003, SD 0.003 f/cc; p=0.20)
  • Indoor total suspended particulates were higher in urban (71.01, SD 38.4 μg/m3) than rural classrooms (52.2, SD 15.1 μg/m3; p=0.05)
  • Airborne lead was higher in urban areas (42.8 ng/m3 indoors, 39.4 ng/m3 outdoors) than in rural areas (14.2 ng/m3 indoors, 12.6 ng/m3 outdoors)
  • The indoor/outdoor ratio of total volatile organic compounds was 2.29 in urban and 2.52 in rural areas, with the highest level in urban classrooms
  • Carbon dioxide exceeded 1,000 ppm in 16 of 54 urban classrooms (29.6%) and in none of the rural classrooms
  • Across all pollutants, the mean indoor/outdoor ratio was 1.96 (SD 0.76)
• The authors' conclusion: The authors concluded that pollutant levels were higher indoors than outdoors and higher in urban than rural areas, and that preschools contain many indoor pollutant sources as well as outdoor ones
• Limitations the authors state:
  • Phase contrast microscopy cannot precisely distinguish asbestos from non-asbestos fibers and is likely to overestimate asbestos if non-asbestos fibers are present
  • Suspected asbestos-containing materials were collected subjectively
  • Possible selection bias, since only the preschools that agreed to participate were evaluated
  • Sampling covered only late spring and summer, when windows are open; winter was not sampled, and the authors expected winter air quality to be worse
  • Geographical and meteorological factors such as wind were not investigated

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