Three units of Sligo fire brigade are tackling a blaze at a recycling depot in the town.
The fire, at the Greenstar Recycling Depot at Deepwater Quay Finisklin, broke out at around 4pm.
Households and businesses in the area are being asked to close their windows as there is now a pungent odour in the air.
Roads in the area are closed to traffic.
People are requested not make any unnecessary journeys within a 5km radius of Sligo town until the fire is under control.