Efficiency of recirculation hoods

Recirculation hoods equipped with carbon and plasma filters are becoming more and more popular. The aim of this study is to determine the effectiveness of recirculation hoods with regard to PM2.5 and NOx removal in a 26 m3 lab kitchen with a gas furnace. With the carbon filter PM2.5 is reduced for about 30%. A fresh carbon filter removed about 60% of the NO2, dropping within a few weeks of cooking to 20%. With the plasma hood NO2 concentrations were above the WHO 1-hour limit and the Dutch health council 15 minutes limit. For plasma hoods it is recommended to optimize odor and particulate matter reduction while minimizing the ozone production. As recirculation hoods have favorable properties in terms of applicability and energy conservation it is recommended to add a particulate filter to recirculation hoods and to apply them preferably in combination with electrical cooking.