NAPLES, Italy — Motorists in Naples will be barred from driving downtown for four hours Sunday under the city’s anti-smog plan.

The ban is from 9 a.m. until 1 p.m. in the city center areas, according to highway traffic signs announcing the plan’s start.

However, U.S. and NATO military and civilians driving vehicles registered with AFI (Allied Forces Italy) plates are exempt from the driving bans, regardless of whether they have had those AFI plates converted to what are called "cover plates," or tags that resemble Italian license plates.

However, because Italian police won’t know at first sight if the vehicles have cover plates, U.S. and NATO motorists might be stopped. Be prepared to present vehicle registration forms to local authorities.