Toxic tire fire: Spanish residents to wear protective masks outdoors (VIDEOS)

Emergency workers stand next to a fire at a tire dump near a residential development in Sesena, south of Madrid, Spain, May 13, 2016. © Sergio Perez
The Spanish government has allowed thousands of residents to return to their homes following a massive tire fire that smothered the town of Sesena in toxic smoke.

Government officials for the central region of Castilla-La Mancha lowered the danger level to zero on Saturday, on condition residents keep their windows shut and wear protective face masks when outdoors.

The level of emissions released in the fire could be as high as the equivalent of pollutants typically produced for the whole of Spain in one year, one environmental organization told El Mundo.

READ MORE: Toxic cloud from tire inferno sees 9,000 residents evacuate Spanish town (VIDEO, PHOTOS)

Environment Minister Jaime Gonzalez attempted to reassure residents by calling the situation “stable” and stressing that the air pollution index “remains negative,” Publico reports.

Up to 9,000 people were evacuated from a nearby apartment complex on Friday night because expected weather conditions raised the risk of smoke engulfing the residential building.

The local government had warned that conditions could favor “the concentration of toxic elements,” which could cause eye and respiratory irritations.

Investigators believe the fire was started deliberately, according to the BBC.

The fire affected three quarters of the five million tires in the illegal tire dump, creating a blaze, which emitted fumes visible from Madrid 30 kilometers (20 miles) away.

The ‘tire cemetery’, which stretches over 10 hectares (25 acres), was originally intended as a temporary spot for recycling tires. However, a massive pile began to form in the 1990s as more tires entered and less left, leaving locals fearing a fire would erupt one day.

"If it caught fire it would be very difficult to put out," Mayor Velazquez said back in 2013.

The dump was declared illegal in 2003 because the company that ran it failed to meet legal requirements. In 2010, a judge ruled the local council was responsible for the abandoned waste.

The town has since struggled to commission a company to take care of the cleanup operation. It hired two separate companies for the job - the first was Senegalese and had no employees, office or previous experience in Spain, and the second turned out to be unlicenced.