HEPA Filtration

Definition

HEPA (High-Efficiency Particulate Air) filtration refers to filters that meet strict standards set by the U.S. Department of Energy: they must capture at least 99.97% of airborne particles 0.3 microns in diameter. Since mold spores typically range from 2-100 microns, HEPA filters effectively trap them during remediation work. True HEPA filters use dense, randomly arranged fibers to capture particles through interception, impaction, and diffusion—not just mechanical sieving like basic furnace filters.

Why It Matters

During mold remediation, disturbing contaminated materials releases millions of spores into the air. Without proper filtration, these spores spread throughout your home, creating secondary contamination and health hazards. HEPA filtration serves two critical functions: negative air machines (NAMs) create containment by filtering air exhausted from the work zone, and air scrubbers continuously clean the ambient air. For homeowners, understanding HEPA filtration helps you verify that contractors are using proper equipment—terms like "HEPA-type" or "HEPA-like" indicate inferior filters that don't meet the 99.97% standard and shouldn't be accepted for mold work.

How It's Used in Mold Work

Professional remediators use HEPA-equipped negative air machines to maintain lower air pressure in the containment area, preventing spore migration to clean zones. The machines pull contaminated air through HEPA filters before exhausting it outside (via ducting through windows) or back into the home. HEPA air scrubbers supplement this by recirculating room air through filters multiple times per hour. After remediation, contractors often run HEPA equipment for 24-72 hours to capture residual airborne spores. IICRC standards require HEPA filtration for all professional mold remediation projects. Equipment rental costs typically run $50-150 per day, and filters must be properly disposed of as contaminated waste.