The Track Fresh Polar Flo Filter is unlike the Regular and Hi-Flow Filters. The Polar Flo Filter has a Coarse Material for trapping Large Particulate Matter and a Carbon Impregnated Felt for trapping Particulate Matter to 2 microns. The Polar Flo filter is designed as a HEPA Filter only, the filter does not filter or trap Carbon Monoxide to our knowledge. Any claim that is does filter Carbon Monoxide in any amount is not a claim of Track Fresh and never has been.