Following installation of the insulation, indoor formaldehyde air levels were raised temporarily, causing irritation to some residents. Formaldehyde is irritating to the eyes, nose, throat and skin and is a skin sensitiser. Formaldehyde concentrations generally returned to background levels within a few days to a few months of UFFI installation. Touching or inhaling breakdown particles of UFFI may cause skin or respiratory irritation, however this does not normally occur except during work that disturbs the insulation.
Whilst formaldehyde is classified as carcinogenic, very low levels of formaldehyde are common in indoor and outdoor air and such levels are not associated with increased cancer risks. More information on cancer risks at different air levels is available from NICNAS.