Local ventilation with depressurization is a depressurization itself and localized fans, which are needed for the exhaust of harmful substances.
Poor ventilation work with a depressurization system along with local fans used for air exhaust contribute to the penetration of various pollutant agents that can come with fresh air. It can be mold or radon, which is contained in semi -passage channels and cellars, and dust from attics. Very often fresh air spoils smoke gases from close bonfires or installations, for heating water, which carry out their work on fuel. Due to weak ventilation, smoke and gas from garages enters the house.