No smoke pipe, most of these houses use the old exhaust fan traditional direct-exhaust method, the housing structure does not reserve space for the transformation of the centralized smoke pipe. Older neighborhoods smoke pollution problems are mainly reflected in the pollution of the building facade, affecting the appearance of the city, fire hazards, pollution of the urban environment, smoke nuisance complaints, kitchen hygiene conditions are poor. The release of the "Wuhan City, old neighborhood renovation technical guidelines", in the environmental requirements, kitchen fumes through the same level of the exterior wall directly to the outdoors, the requirements of the outdoor exhaust port set up to avoid the wind, rain and prevent pollution of the wall components, kitchen hood selection of high-efficiency smoke purification devices.