Nowadays, ceramic kilns burn wood but also a lot of waste as fuel (e.g. treated wood, tyres and used oil collected by waste pickers from landfills and sold to potters), which causes a great deal of air pollution and contaminates the soil. The unbumed refuse is discharged into landfills or nature. The same situation occurs in bathhouses (of which there are approximately 5,000 across the country), which have ovens that use some waste as fuel. These studies show that most hazardous waste is stored in situ, at the production sites (235,561 tons in 2008 alone). The risk of pollution is highest at the storage sites.