title: Formaldehyde and carbon dioxide air concentrations and their relationship with indoor environmental factors in daycare centers.
abstract: The aim of this study was to measure the air concentrations of carbon dioxide (CO2) and formaldehyde (HCHO) in daycare centers to determine relevant influencing factors, including temperature, relative humidity (RH), type of facility, number of children, type of ventilation system, ventilation time, and air cleaning system. The authors measured HCHO, CO2, temperature, and RH in the center of classrooms in 289 daycare centers. Spearman's correlation and Mann-Whitney analyses were used to examine the relationships and differences in HCHO and CO2for varying temperatures, RH values, and categorical indoor environmental factors. There were no significant differences in the HCHO and CO2air concentrations with varying numbers of children, ventilation times, or ventilation and air cleaning system types. However, both the HCHO and CO2air concentrations were significantly different for varying RH values, which were divided into five categories (p < 0.001). Only the HCHO air concentrations were significantly different for varying temperatures, which were divided into five categories (p < 0.001). Significant correlations were found between HCHO air concentrations and the temperature (r = 0.35, p < 0.0001), RH (r = 0.51, p < 0.0001), and CO2(r = 0.36, p < 0.0001). The study results support maintaining an appropriate temperature and RH range for reducing airborne HCHO in daycare centers. Further research is needed to elucidate the precise mechanisms responsible for the relationships observed in this study.
  
  
  
  Data from 289 daycare centers in Seoul, South Korea, indicate that HCHO concentrations show a positive correlation with indoor temperature and relative humidity. This indicates that keeping temperatures low will help keep HCHO concentrations low, by both a direct and an indirect effect, since low temperatures also cause low relative humidity.
authors.affiliation: a National Cancer Control Institute , National Cancer Center , Goyang , South Korea.
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Hwang
authors.affiliation: b Seegene Medical Foundation , Seoul , South Korea.
authors.forename: Gil Bong
authors.initials: GB
authors.lastname: Lee
authors.affiliation: c Graduate School of Environmental Studies , Kwangwoon University , Seoul , South Korea.
authors.forename: Im Soon
authors.initials: IS
authors.lastname: Kim
authors.affiliation: d Institute of Environmental and Industrial Medicine , Hanyang University , Seoul , South Korea.
authors.forename: Wha Me
authors.initials: WM
authors.lastname: Park
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis*; D002648:Child; D003430:Cross-Sectional Studies; D003631:Day Care, Medical; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005557:Formaldehyde / Q000032:analysis*; D006801:Humans; D056910:Republic of Korea; D011795:Surveys and Questionnaires
chemical_list: D000393:Air Pollutants; D002245:Carbon Dioxide; D005557:Formaldehyde