Why Silica Dust Reappears 48 Hours After Cleaning
Standard cleaning displaces silica particles into the air where they remain suspended for 24-72 hours before resettling. This is "The Settling Error" - why silica dust reappears on surfaces 48 hours after the cleaner left, creating the illusion that your new build was never cleaned at all.
The Physics of Silica Settling
Crystalline silica particles from drywall, concrete, and masonry work range from 0.1 to 10 microns in diameter. At this size, they behave more like gas molecules than dust - remaining airborne for extended periods due to Brownian motion and air currents.
Settling Time by Particle Size
10 μm
Large particles
~3 hours to settle 3 feet
1 μm
Fine particles
~12+ hours to settle 3 feet
0.3 μm
Respirable silica
~72+ hours (stays airborne)
Why Standard Cleaning Fails
When a standard cleaning crew wipes, sweeps, or vacuums without HEPA filtration, they accomplish two things:
- Surface displacement: The visible dust moves from surfaces into the air column
- Particle redistribution: HVAC systems circulate these particles throughout the structure
The result: surfaces appear clean at handoff, but 24-72 hours later, the suspended particles settle back onto every horizontal surface. This is "The Settling Error."
The Solution: Negative Air + HEPA Extraction
Negative Air Machines
Industrial air scrubbers create negative pressure, continuously pulling contaminated air through HEPA filters. This captures particles before they can resettle - eliminating the settling error at its source.
HEPA H13 Extraction
True HEPA H13 filters capture 99.97% of particles at 0.3 microns - the most penetrating particle size. This includes respirable crystalline silica that standard vacuums simply recirculate.
The CTC Protocol
Phase 1
Deploy negative air
Air scrubbers run 4+ hours before surface cleaning begins
Phase 2
HEPA surface extraction
All vacuuming uses true HEPA H13 equipment only
Phase 3
Post-clean air cycle
Negative air runs 2+ hours after surface work completes
OSHA Silica Standards
The Occupational Safety and Health Administration sets a Permissible Exposure Limit (PEL) of 50 μg/m³ for respirable crystalline silica. Post-construction environments routinely exceed this threshold without proper remediation.
50 μg/m³
OSHA PEL Limit
8-hour time-weighted average
200-500 μg/m³
Typical Post-Construction
Without proper remediation
Eliminate The Settling Error
Clean Town & Country deploys negative air machines and HEPA H13 extraction on every post-construction project in St. Louis. No settling. No callbacks.