Mice are used for inhalation and skin studies because they're cheap, we know their genome, they have a short lifespan for whole lifecycle observation and they're ideal for mapping to human respiratory and skin responses.
These comments are filled with people who believe that everyone else here is dumber than they are. Leaving shallow dismissive comments explaining something that doesn't need to be explained is like crack to them.
The migration from mouse models to human understanding is long and complex, and although it's a meme, "in mice" is a good shortcut for saying "This is a good start, but it's not ready to extrapolate into conclusions against the impact to human beings".
> "The team bred four strains of mice.
> They then exposed the mice to a single dose of the liver carcinogen diethylnitrosamine (DEN).
> DEN is found in tobacco smoke."
They simulated the "consequences" of smoking in mice.