Tohoku J. Exp. Med., 2001, 195 (4)

Sampling Methods and Residential Factors Affecting Formaldehyde Concentration in Indoor Air

YOKO ENDO, TAKEJI MIYAZAKI,¹ YOKO HIKITA,² MICHIYO AZUMA,²
HIROKI IKEDA,³ KENJI FUKUNAGA and GINJI ENDO⁴

Department of Public Health, Kansai Medical University, Moriguchi 570-8506,
¹Department of Occupational Hygiene, Osaka City Institute of Public Health and Environmental Sciences, Osaka 543-0026,
²Department of Residential Environment and Design, Division of Human Environment, Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506,
³Department of Otorhinolaryngology, Kansai Medical University, Moriguchi 570-8506, and
⁴Department of Environmental Health, Medical School, Osaka City University, Osaka 545-8585

Formaldehyde (HCHO) is the most serious residential pollutant. In order to evaluate residential HCHO levels, two sampling methods have been recommended; one is a 30 minute sampling in a closed room, and the other is a 24 hour sampling with an ordinary lifestyle routine. The aim of this report was to clarify the difference between the HCHO levels obtained by the two sampling methods. Residential air in 58 rooms was sampled for 30 minutes by an active sampling method more than 5 hours after residents closed windows, and by a passive sampling method for 24 hours with an ordinary lifestyle routine. The HCHO concentration with the 30 minute sampling was 0.118±0.065 ppm (range: 0.034-0.295 ppm) and 36 rooms (62%) exceeded the Japanese guideline value of 0.08 ppm, while 5% were higher than 0.25 ppm. The HCHO concentration with the 24 hours sampling was 0.053±0.039 ppm (range: 0.02-0.167 ppm) and only 13 rooms (22%) exceeded 0.08 ppm. The relationship between the concentrations obtained by the two methods was linear. However, the level with the 24 hour sampling significantly reduced with prolonged window opening time, meaning that occupants made an effort to reduce the usual exposure to about 40% of the exposure in a closed room by opening windows in order to escape from irritation. Since major adverse effects of HCHO are irritation and sensitization, the occasional peak concentration must be focused. In order to evaluate residential HCHO levels, measurement in a closed room is recommended even if people are living there.

Keywords —— formaldehyde; 2, 4-dinitrophenylhydrazine; indoor air; active sampling; passive sampling

© 2001 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2001, 195, 227-236

Address for reprints: Yoko Endo, Department of Public Health, Kansai Medical University, Moriguchi 570-8506, Japan.

e-mail: endo@tnoc.kmu.ac.jp