Air scrubbers, also known as negative air machines, aggressively clean the air of hazardous particulates, chemicals, and gases left behind by water, mold, chemical, or fire damage. These heavy-duty air cleaners work by pulling in contaminated air, passing it through HEPA-grade air filters, and exhausting clean air back out into a space or into a separate area through ductwork. When ducted, a HEPA air scrubber creates negative air pressure, which helps to limit the spread of contaminants to surrounding areas. By design, air scrubbers have extremely large CFM (cubic feet per minute) rates. Some models can clean as much as 2,000 cubic feet of air per minute.