Air scrubber
Also called: HEPA air scrubber, negative air machine, air filtration device, AFD, HEPA scrubber
A portable fan that pulls room air through a pre-filter and a HEPA filter and returns it clean, used in mold and water-damage remediation to capture airborne spores and dust inside the containment. $100–$200 a day to rent; ducted outdoors it becomes a negative air machine. Not an air purifier.
Remediation makes the air dirty on purpose — cutting, scraping and bagging release what was growing in the wall — and the scrubber is what cleans it back up while the work happens. A 500–2,000 CFM unit with a true HEPA filter (99.97% at 0.3 microns) recirculates the air in a sealed room several times an hour; inside a containment it runs from before the first cut until after the final wipe-down, and often for a day beyond.
Two ways to use it. Recirculating — the unit sits in the work area and blows filtered air back into it, reducing airborne spore counts. Exhausting — flexible duct on the outlet runs out a window, so the unit pulls air out of the containment, creating the negative pressure that keeps spores from escaping; the same machine then goes by the name negative air machine. Larger jobs run one of each.
Rentals are $100–$200 a day from equipment yards and restoration suppliers, with filters charged separately; a remediator’s quote includes them as equipment days. Things that are not air scrubbers: household HEPA purifiers (far too little airflow for remediation), ozone generators (hazardous to breathe and don’t remove anything), and foggers. After remediation, clearance testing checks whether the air is actually clean.