Advertising on fire trucks

On my way home tonight, I passed some kind of scene surrounded by several fire trucks. One of the trucks was departing and drove in front of me for awhile before turning off to the EMT station by Lake Calhoun.

At some point I noticed something odd about the truck–there was an advertisement on it! It was on a canvas sheet that covers the hose storage area (a decent chunk of the back side of the truck).

It was for Quit Plan, which is interesting, as both help people stop smoking 😉

So the question is: can anyone advertise there? or it only for public service type messages?

Will we see “This fire rescue brought to you by Mennen” one day? How about “The arrest is sponsored by Tropicana” (a bad brand experience for one person to be sure)?

Has anyone else seen these firetruck ads?