Why a HEPA Air Scrubber Is Required for Mould Remediation

Mould remediation is one of the most regulated cleaning operations in the trades. The IICRC S520 standard, OSHA respiratory protection rules and most state EPA programs all require HEPA filtered air movement during active mould work. A HEPA air scrubber is the workhorse machine that meets those standards and protects both the workers and any occupants who return to the space.

What an Air Scrubber Does

A HEPA air scrubber pulls air through a sequence of filters and exhausts cleaned air. The filter train is typically a coarse pre filter, an optional carbon filter and a true HEPA element rated to 99.97 percent capture at 0.3 microns. On a mould job, the scrubber is set up to draw air OUT of the contained work area, creating negative pressure that prevents spore migration.

How to Size for the Job

Air scrubber sizing is based on air changes per hour (ACH). For mould remediation, IICRC S520 recommends a minimum of 4 ACH for general work and up to 6 to 12 ACH for active demolition. Calculate as follows:

1. Measure the contained work area in cubic feet (length x width x height)
2. Divide by 60 (minutes per hour) to get airflow per minute needed for 1 ACH
3. Multiply by your target ACH

Example: a 1000 cubic foot bedroom needs 67 CFM at 4 ACH or 200 CFM at 12 ACH. A single 500 CFM scrubber covers the work easily. For 5000+ cubic foot spaces, run two scrubbers in parallel.

Browse HEPA air scrubbers from 500 to 2000 CFM.

Negative Air Setup

Connecting the scrubber's exhaust to a duct that vents outside the contained area creates negative pressure. Air from outside the work area gets pulled IN through any leak path, and contaminated air can only leave through the HEPA filtered scrubber. Most professional crews use 6 mil poly sheeting and zip walls to seal the work area, with a single negative air machine ducted through a window or vent.

Filter Train

• Pre filter. Replaceable foam or fibre. Catches large debris. Replace daily on dusty jobs.
• Activated carbon filter. Optional. Reduces musty odours during remediation. Replace every 30 to 60 days.
• HEPA filter. The certified primary. Replace annually or when pressure drop indicates saturation.

Drying After Mould Cleanup

Mould thrives in moisture. After remediation is complete, the underlying water source must be addressed and the area dried below 60 percent relative humidity. Pair the air scrubber with a commercial dehumidifier sized to the room. A 70 pint LGR dehumidifier handles most residential mould rooms; larger spaces need 90 to 200 pint capacity.

Containment Equipment

For ICRA Class 4 work or any remediation requiring three stage decontamination, pair the air scrubber with mobile containment systems that include a clean room, shower compartment and dirty PPE removal area.

Maintenance

Inspect the pre filter daily. Vacuum (HEPA) the housing weekly. Test the seal on the HEPA element with a smoke pencil quarterly. Document filter changes for compliance and to support customer reporting.

The HEPA air scrubber is the single most important piece of equipment on a mould job. The quality of the spore capture, the dryness of the rebuilt area and the safety of the occupants all trace back to a properly sized, properly sealed scrubber running long enough to meet the air change requirements.