Over time dust accumulates on household surfaces. As well as making the surfaces dirty, when dust is disturbed it can become suspended in the air, causing sneezing and breathing trouble. It can also transfer from furniture to clothing, making it unclean. Various tools have been invented for dust removal; Feather and lamb’s wool dusters, cotton and polyester dust cloths, furniture spray, disposable paper "dust cloths", dust mops for smooth floors and vacuum cleaners. Vacuum cleaners often have a variety of tools to enable them to remove dirt not just from carpets and rugs, but from hard surfaces and upholstery.