Turns out formaldehyde containing UF-insulation foam is still legal and still being used in the Netherlands to fill double-skin walls. The limits (120μg/m³) were set in 1978 and are for a maximum of 30 minutes due to respiratory concerns. Many houses insulated with this UF-foam emit concentrations much higher than this limit, but as formaldehyde is a neurotoxin there is no safe dose (much like lead).
Funnily enough UF-foam has been banned in North America since the 80s, why are we still using this exactly?! You can even get government subsidies for installing this.