Data Centres Aren't Cleanrooms. So Why Does Dust Still Matter?
Ask a data centre manager what cleanliness class their data hall runs at and you'll usually get a puzzled look. That's fair, because nobody gowns up to swap a drive.
But every server breathes room air around the clock, and whatever is in that air ends up on heat sinks, fans and circuit boards. The useful question isn't "are we a cleanroom?" It's "how do you stop dust getting into a data centre, and stop it moving once it's inside?"
Dust Arrives From Two Directions
Contamination has two broad sources:
• Inside-out: debris from floor tiles, cardboard fibres and dust disturbed during maintenance.
• Outside-in: material carried in on shoes, trolley wheels and packaging.
Filters only catch what is already airborne. Floor-level dust stays out of their reach until foot traffic, a server lift or a lifted tile puts it back into the airflow.
Zinc Whiskers: The Contamination You Didn't Bring In
The most cited example of data centre dust doesn't come through the door. NASA's Goddard Space Flight Center documented zinc whiskers growing on the zinc-coated steel underside of raised floor tiles. The debris was shed especially during maintenance, distributed around the room by the air cooling system and drawn into servers, routers and disk arrays. Because the fragments are conductive, NASA links them to catastrophic or intermittent short circuits.
No entrance mat stops zinc whiskers. They grow inside the room and are managed through tile inspection, careful handling and replacement. The broader lesson is that anything on or under the floor can become airborne contamination.
How Cooling Systems Turn Floor Dust Into a Hardware Problem
Data halls move a lot of air, so settled particles don't stay settled. Once dust reaches hardware, three things can happen:
• It coats heat sinks and components, which makes heat harder to get rid of.
• It loads fan intakes and filters.
• Some dust absorbs moisture and can become conductive or corrosive. ASHRAE guidance recommends that the deliquescent relative humidity of particulate contamination should be above 60% RH.
There is an ISO class here. The ASHRAE TC 9.9 contamination white paper states that data centres must meet ISO 14644-1 Class 8 and be free of zinc whiskers. It also suggests MERV 8 filtration for room air and MERV 11, or preferably MERV 13, for incoming air.
Where Outside-In Dust Actually Enters
Footwear contamination control is mostly about mapping traffic routes. In most facilities, look at:
• Loading bays and goods-in, where trolleys cross from external surfaces.
• Unboxing areas. ASHRAE advises unpacking equipment outside the data hall.
• The corridor between office space and the white space.
• Contractor routes used during fit-outs and maintenance windows.
Contamination Control Polymeric Matting at Transition Points
Why People Look for a Sticky Mat Alternative
Peel-off tacky mats work by adhesion, so their performance depends on how often someone peels the top sheet. A loaded sheet captures less, and every peeled sheet becomes waste. Polymeric contamination control mats take a different approach.
-Capture Method
Peel-off tacky mat: Adhesive top sheet
Polymeric contamination control mat: Polymer surface, cleaned in place
-Maintenance
Peel-off tacky mat: Peel and discard used sheets
Polymeric contamination control mat: Washable with routine cleaning
-Service Life
Peel-off tacky mat: Single-use sheets
Polymeric contamination control mat: 3–5 years (manufacturer data sheet)
-What to Check
Peel-off tacky mat: Supplier’s peel schedule and performance data
Polymeric contamination control mat: Independent test reports
What the Evidence Shows for Washable Cleanroom Mats
When buyers search for "ISO Class 5 mats", the useful question is what was actually tested. For CC Matting's heavy-duty polymeric mat:
• Particle removal: In a February 2026 CPC Laboratories study, shoes dirtied on a warehouse floor then taking three steps on the mat showed an average 91.8% removal of particles above 5 µm. Trolley wheels rolled across 90 cm of mat showed 90.1% removal. Particles above 100 µm were fully removed in both tests. Results apply to the study conditions only.
• Particle emission: Fraunhofer IPA qualified the material as suitable for ISO Class 5 air cleanliness, based on particle emission under friction testing.
• Static: TUS Athlone measured a surface resistivity of 1010 Ω/sq, which is in the static-dissipative range.
Reusable Cleanroom Matting Is One Layer, Not the Strategy
Cleanroom entrance mats only help if feet and wheels actually cross them, so size and place them where traffic can't step around. Combine contamination control matting with filtration, tile management, unboxing discipline and cleaning. Contamination control flooring supports a process, but it doesn't replace one.
Frequently Asked Questions
How do you stop dust getting into a data centre?
Combine filtered incoming air, controlled entry routes, contamination control mats at transition points, unboxing outside the data hall and regular cleaning. Treat floor-level and airborne dust as separate problems, because filters only catch particles once they're airborne.
What are zinc whiskers in a data centre?
Zinc whiskers are fine conductive filaments that can grow on zinc-coated steel, including some raised floor tiles. NASA documented debris shed during maintenance being carried by cooling airflow into servers, where it can cause short circuits.
What cleanliness level should a data centre meet?
ASHRAE TC 9.9 guidance states that data centres should meet ISO 14644-1 Class 8 and be free of zinc whiskers. That is far less strict than a pharmaceutical cleanroom, but it is still a measurable target.
Are tacky mats suitable for data centres?
Tacky mats capture footwear contamination, but performance depends on consistent peeling, and each sheet becomes waste. Some sites prefer a washable polymeric mat. Either way, ask for independent test data.
Should data centre mats be static dissipative?
Where electrostatic discharge is a concern, static-dissipative surfaces are worth specifying as one part of an ESD control programme. Ask for surface resistivity test results, not just product descriptions.
Next Step
If you're mapping where dust enters your facility, the data centre contamination control page explains how CC Matting approaches transition zones. The test reports and certifications behind the figures above are listed on the compliance page. As a contamination control mat supplier, CC Matting installs in Ireland and the UK and distributes worldwide. Get in touch to discuss your site.