Commercial office cleaners normally carry out their work at night so as not to disturb the work force. Some companies have clear desk policies which mean that all papers and files should be put away in drawers so that the cleaners can clean effectively. As with other buildings, dust and grime gather in certain areas, especially around drinks machines, in kitchen areas and in carpets. They need to be thoroughly cleaned regularly not only for hygienic purposes, but to reduce the amount of dust in the air. Upholstery also gathers dust, so chairs and meeting room furniture should be cleaned frequently. Health and safety is paramount in a working environment, and walkways and corridors should be kept free of clutter not only to prevent accidents, but to allow easy vacuuming. It is all too easy to allow unused items to be pushed out of the way on top of cupboards and in walkways, especially if the office is short of storage space. However, for the office to be cleaned properly they must remain easy to access.