Indoor formaldehyde levels had been measured comparatively by active and passive sampling method. The 5 study sites were Chulalongkorn Hospital, Police hospital and Ramathibodi hospital. The results revealed that formaldehyde levels in anatomy laboratory Chulalongkorn hospital was 107.57+-36.15 ppb (for active sampling) and 148.94+-36.66 ppb (for passive sampling), cadaveric storage room Chulalongkorn hospital was 363.85+-164.94 ppb (Active) and 411.86+-162.07 ppb (Passive), pathology laboratory Police hospital was 224.99+-138.46 ppb (Active) and 230.99+-50.73 ppb (Passive), autopsy room Ramathibodi hospital was 206.52+-55.87 (Active) and 246.49+-54.68 ppb (Passive), pathology laboratory Ramathibodi hospital was 206.15+-39.16 ppb (Active) and 248.47+-39.47 ppb (Passive) while the control area (the FT-IR laboratory of STREC) was 13.63+-1.29 ppb (Active) and 17.79+-1.43 ppb (Passive). The association between two methods are found statistically significant and the formaldehyde levels were much more than Time-Weighted Average Standard of Occupational Safety and Health Administration (100 ppb). The results from questionnaire were shown that the most staffs in hospital's laboratory had these symptoms; sore throat, eye irritate and headache. Risk assessment indicated that cadaveric storage room Chulalongkorn hospital was the highest risk of environment and health.
