More than 100 firefighters were needed to control a massive blaze at Coolaroo.

The fire started at SKM Recycling around 3.30am on Tuesday morning.

More than 100 workers at the factory were evacuated.

A watch and act message was issued for a number of communities north of Melbourne.

Campbellfield, Dallas and Coolaroo residents have been told to keep windows closed due to the smoke.

One person has been treated for breathing problems but didn’t need to go to hospital.

The fire was contained shortly after 8am.