The blaze started at the Eco-X rubbish depot in Pomezia on Friday morning, and the cloud of smoke was visible from several kilometres away.
Firefighters said late on Friday morning that "the dense column of smoke is under control, and for the moment has not affected inhabited centres".
However, both the fire service and the local health authority of Pomezia, the town where the depot was located, warned locals to keep windows closed "in homes, schools, offices, and health and social care structures", keep animals inside, and to avoid all unnecessary travel.
Clouds of smoke are visible from Rome after a huge fire at a nearby waste depot. pic.twitter.com/oAvw60yS4T— The Local Italy (@TheLocalItaly) May 5, 2017
The health authority also advised residents to "wash with great accuracy" any homegrown fruits or vegetables over the next few days.
Pomezia mayor Fabio Fucci ordered the evacuation of all schools within a two-kilometre radius of the incident were evacuated, as well as banning outdoor sports and "other planned outdoor events".
No injuries had been reported as a result of the fire, emergency services said.
It is not yet clear what started the blaze, though Pomezia's town council said at around midday: "According to the latest information, it seems that the material which caught fire was plastic, which is causing a black cloud visible from all parts of the town."
Pomezia, shown on the map below, is part of the Metropolitan City of Rome and lies about 30km south of the capital's historic centre.
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