Quick answer: HEPA air scrubbers capture at least 99.97 percent of particles 0.3 microns in size, which includes mold spores. Pros use them to clean the air and, when ducted outside the work area, as negative air machines that keep spores contained. A home HEPA purifier can lower airborne spores in a room, but it can't remove mold growing on surfaces or fix moisture.

What "HEPA" Means

HEPA stands for high-efficiency particulate air. Under the U.S. Department of Energy standard, a true HEPA filter captures at least 99.97 percent of particles 0.3 microns in diameter, the size that is hardest to catch. Larger and smaller particles are captured even more efficiently. Most mold spores are a few microns or larger, so a sealed HEPA system catches them well.

Watch out for labels like "HEPA-type" or "HEPA-like." Those filters don't have to meet the 99.97 percent standard.

Questions about one specific room are worth putting to our company.

Air Scrubbers vs. Negative Air Machines

Pros use the same kind of machine in two ways:

Setup	How it works	Purpose
Air scrubber (recirculating)	Pulls air from the room through filters and blows clean air back into the same space	Lowers airborne spores and dust during and after work
Negative air machine	Pulls air from inside a containment area and exhausts it outside the containment, often through a window	Creates negative pressure so air leaks into the work area, not out to the rest of the house

Negative pressure is the key to containment. When the work area is under slightly lower pressure than the rest of the home, any gap in the plastic lets clean air flow in instead of letting spores escape. You'll often see the plastic sheeting bow inward slightly, which is a quick visual check that it's working.

Dehumidifier and hygrometer running during the drying phase

How Scrubbers Are Used During Remediation

Setup: the work area is sealed with plastic, HVAC vents are covered and machines are placed and ducted.
During removal: machines run continuously while moldy materials are cut out, sanded or HEPA vacuumed.
Detail cleaning: surfaces are HEPA vacuumed and wiped while machines keep scrubbing the air.
After work: machines often run for a period after cleaning to capture settling particles before containment comes down.
Verification: a visual inspection and, when recommended, independent clearance testing.

Machines are sized to the space so the air is filtered several times per hour. Pre-filters catch larger dust so the HEPA filter lasts longer. Used filters are bagged and disposed of carefully, since they are full of what they captured.

Tip: Ask any contractor how they'll control airflow. A good answer includes plastic containment, sealed HVAC vents and HEPA machines creating negative pressure. The EPA's remediation guide describes these same controls.

Room mid-remediation with contents bagged and framing exposed

HVAC Work and Air Scrubbers

Air scrubbers are especially important in HVAC remediation. Cleaning ducts, the blower and the mold on the AC coil and drain pan knocks spores loose right in the airstream. A HEPA negative air machine connected to the duct system pulls that debris out, while scrubbers in the room around the air handler catch anything that escapes.

Can I Stay Home While Scrubbers Run?

Often, yes. With good containment and negative air, many families stay home during smaller projects, while avoiding the work area. The machines do make steady fan noise, and they may run overnight. Larger jobs or households with someone who has asthma, allergies or a weakened immune system may be better off leaving. Our guide to staying home during mold remediation covers how to decide, and anyone with health concerns should check with their doctor.

HEPA vacuum and brushes beside a partly cleaned framing bay

Do Home HEPA Air Purifiers Help With Mold?

A true HEPA room purifier can lower the number of spores floating in a room. That can help sensitive people feel more comfortable. But it has real limits:

It doesn't remove mold growing on walls, wood, carpet or in HVAC equipment.
It doesn't fix the moisture problem feeding the mold.
Most home units are sized for one room, not a whole house.
Spores that settle on surfaces aren't reached by the purifier.

The EPA is clear that the key to mold control is moisture control. Use a purifier as a helper, not a fix. Keeping indoor humidity below 60 percent, ideally 30 to 50 percent, does more to prevent mold than any purifier.

HEPA air scrubber running with ducting routed out of a window

Scrubber vs. Home Purifier at a Glance

Feature	Professional HEPA air scrubber	Home HEPA purifier
Airflow	High, sized for work areas	Lower, sized for a room
Negative pressure	Yes, when ducted outside containment	No
Use	During and after remediation	Everyday comfort
Removes growth on surfaces	No; paired with physical removal	No

When to Call a Professional

If you have mold in your HVAC system or a room served by forced air, containment and HEPA filtration are what keep a cleanup from spreading. Our HVAC and air duct mold remediation service in Gettysburg uses HEPA negative air on every job and follows the IICRC S520 standard. Call (717) 420-8919, 24 hours a day.