Abstract: A device for filtering air comprising a filter housing having an air inlet for directing flow of air drawn into the housing from atmosphere and an air outlet for directing flow of air exhausted from the housing to atmosphere, the air drawn into the housing carrying air contaminants therewith. A plurality of cylindrical filter stacks having substantially parallel longitudinal axes are disposed in the housing. The filter stacks have outer cylindrical filter walls and inner passages extending therethrough along the longitudinal axes. The filter stacks are capable of filtering the air drawn into the housing by trapping the air contaminants in the filter walls when air is drawn through the filter walls into the inner passages.