Indoor air guideline levels for formic, acetic, propionic and butyric acid

Evaluation of sensory and health effects from indoor air exposures is hampered by the limited number of specific indoor air standards and guidelines. It is proposed that the evaluations be based on three values for each compound, an odour threshold, a value set for prevention of irritation of eyes and nose (sensory irritation) while all other non-genotoxic effects (including lung effects) are included in the category "health effects" and evaluated by means of a single value. Finally, it is also evaluated whether the substance is a genotoxic carcinogen. Indoor air guideline values are proposed for formic, acetic, propionic and butyric acid, based on published literature. For each substance the lowest of the proposed sensory irritation and health effect values was higher than, but otherwise in reasonable agreement with, established occupational exposure limits (OEL) multiplied by 1/40. This suggests that the OELs may play an important role in evaluations of the types of indoor air exposure effect mentioned.