The entire house should be cleaned before New Year's Day. On New Year's Eve, all brooms, brushes, dusters, dust pans and other cleaning equipment are put away. Sweeping or dusting should not be done on New Year's Day for fear that good fortune will be swept away. After New Year's Day, the floors may be swept. Beginning at the door, the dust and garbage are swept to the middle of the parlor, then placed in the corners and not taken or thrown out until the fifth day. At no time should the garbage in the corners be trampled upon. In sweeping, there is a superstition that if you sweep the dirt out over the threshold, you will sweep one of the family away. Also, to sweep the dust and dirt out of your house by the front entrance is to sweep away the good fortune of the family; it must always be swept inwards and then carried out, then no harm will follow. All dirt and garbage must be taken out the back door.
http://web.uvic.ca/~mroth/438/CHINA/taboos.html