Ecology units are ventilation equipments whose use is recommended in kitchen exhaust systems , which serve to clean greasy and dirty exhaust air . With the increase of environmental consequences in the 21st century , severe restriction have been imposed on the release of industrial wastes to the environment , and particularly on the release of flue gas and kitchen exhaust systems to the atmosphere. It is known that the volatile organic compounds ( VOC ) and other particular based substances in the kitchen exhaust systems creates a huge pollution in the air . in many countries , significant restrictions have been imposed on the release of odorous substances to the atmosphere by the regulation issued by the Ministeries of the Environment.

With the introduction of the new residential concept in big cities the rise in so-called “ all-in-one “ projects has led to some problems with air quality . This is because the concentrated kitchen exhausts from the large restaurants and dining areas in these projects have a negative impact on the daily functioning of people occupying the residential , office , and hotel areas that are in close proximity to these areas.