Originally Posted by
jerumagrinberga
It may very well be a UK gov requirement(link available?) but BA at least is claiming that they're mandated to do so by the WHO(does the WHO even have legal competency to require this?).
I don't believe that BA do claim that. IIRC the announcement says that they are required by law to spray and that the spray in question has been approved by WHO.
The law in question is presumably that of the destination country.