Authorities ordered residents to stay indoors and shut windows in parts of the central Spanish town of Sesena.
Firefighters were called during the night to tackle the blaze which threw clouds of thick black smoke to the air.
Sesena town mayor told a local radio station that residents in three districts had been asked to stay at home until the fire was extinguished and the smoke dispersed.
Police said classes at one school had been canceled.
Authorities urged drivers on nearby roads to close their windows.
According to the town mayor, the fire appeared to have been started intentionally on Friday.
Some 10 firefighter units were sent to extinguish the blaze at the dump located some 35 kilometers (22 miles) south of the capital, AP reported.
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