Formaldehyde, Methanal
Formaldehyde is an aldehyde expressed by the chemical formula HCHO.
Although it is not considered as malodorous substance by the Offensive Odor Control Act, its toxicity and carcinogenicity is extremely high (categorized as group 1 (confirmed to be carcinogenic to humans)). A guide line level of 0.08ppm has been established by the WHO, and the Ministry of Health, Labor, and Welfare of Japan has determined this value for as an allowable concentration level for living accommodations.
Formaldehyde is used in extremely large quantities as an industrial raw material and is a structural component for resins and adhesives. It is a volatile organic compound (VOC) and one of the causative substances of sick house syndrome.
It is known that in nature these VOC are also widely emitted through metabolization. Although in quantities that do not affect human health, these VOC are emitted at rather high concentrations in some fish and mushrooms.