Patent ID: 7601189

Claim:
A filtering method for removing impurities from air ( 24 ) circulating within a limited space, such as a room, an air raid shelter or a vehicle, according to which filtering method the air ( 24 ) to be filtered containing carbon dioxide and impurities generated within the limited space is passed through a filter ( 13 ), whereby at least a portion of the carbon dioxide and impurities in the air is trapped in the filter, and after the filtering, the filter ( 13 ) is regenerated to remove the carbon dioxide and impurities trapped in the filter by passing a gaseous regenerating medium through the filter, characterized in that the filter ( 13 ) is a carbon dioxide filter ( 13 ) for trapping and removing carbon dioxide and the air ( 24 ) to be filtered is passed through the carbon dioxide filter ( 13 ), so that at least a portion of the carbon dioxide in the air is trapped in the filter and removed from the air ( 24 ), and after the filtering, the carbon dioxide filter ( 13 ) is regenerated by removing the carbon dioxide trapped in the filter by a technique whereby air ( 24 ) that, prior to being conducted to the filter, has been heated to a temperature of 50-200° C., is passed through the filter.