A hospital ward, a ready-to-eat food line and a sterile fill suite answer to different regulators. Yet cross-contamination in all three follows the same route: something is picked up in one area, carried on a person, wheel or container, and released where it should never have reached.
Because the chain is predictable, prevention can break it at the boundary instead of relying on cleaning afterwards.
The four links in every cross-contamination event
• Source: a lower-grade area, soiled surface, raw material or infected patient.
• Carrier: footwear, trolley wheels, gloves, packaging or mobile equipment.
• Route: the corridors, doorways, airlocks and lifts carriers move through.
• Receptor: a patient, open product, exposed food or critical surface.
Cleaning targets the first and last links. Persistent problems usually sit in the middle two.
Three sectors, one shared weak point
Healthcare: the floor nobody touches
Floors are rarely treated as a transmission surface. Yet infection-prevention research has found hospital floors frequently contaminated with healthcare-associated organisms, which reach hands via bags, cables and dropped items. Footwear and bed wheels then move that load between rooms. Healthcare contamination control mats at theatres, isolation areas and aseptic pharmacy units act on the carrier, not just the room.
Food manufacturing: zoning breaks down at the wheels
Food sites rely on hygienic zoning. Standards such as BRCGS distinguish low-risk, high-care and high-risk areas, with dedicated footwear and boot washes at the transitions. The weak point is often wheeled traffic: pallet trucks and trolleys cross zones more often than people and frequently bypass footwear controls.
Pharmaceuticals: the threshold is written into the strategy
EU GMP Annex 1 requires sterile manufacturers to maintain a documented contamination control strategy (CCS) covering personnel, material and equipment flows. Pharmaceutical contamination control mats typically sit at gowning-room and material-airlock entrances, as one layer alongside gowning, airflow, cleaning and monitoring.
Why prevention belongs at the threshold
Once particles cross a boundary, foot traffic redistributes them and air movement resuspends them, so the area needing cleaning grows. A threshold is the one narrow, predictable point every carrier passes through. Effective footwear contamination control there needs enough contact for each sole and wheel, retention so captured material is not released again, and performance that stays consistent between maintenance cycles.
The sticky mat alternative: how threshold control has evolved
For decades the default was the peel-off tacky mat: an adhesive film whose top sheet is removed once loaded. Capture weakens as the sheet fills, peeling can disturb captured material, and each layer becomes plastic waste. As a tacky mat alternative, polymeric contamination control mats use a reusable polymer surface that is cleaned in place.
1. Renewal
Peel-off tacky / sticky mat: Top sheet peeled and discarded.Polymeric contamination control mat: Cleaned in place.
2. Between Changes
Peel-off tacky / sticky mat: Capture declines as the sheet loads.
Polymeric contamination control mat: Surface restored by routine cleaning.
3. Waste
Peel-off tacky / sticky mat: Every layer is single-use plastic.
Polymeric contamination control mat: Reusable, with a stated lifespan of 3–5 years.
4. Wheeled Traffic
Peel-off tacky / sticky mat: Sheets can lift under heavy wheels.
Polymeric contamination control mat: Particle removal tested on trolley wheels and footwear.
Contamination control polymeric matting: what the evidence shows
In an independent CPC Laboratories walk-off study, shoe soles and plastic trolley wheels loaded with warehouse floor dirt were passed over CCM Heavy Duty polymeric matting. Average removal of particles larger than 5 µm was 91.8% from footwear and 90.1% from wheels; particles over 100 µm were fully removed. The report states results apply only to its materials and method.
A threshold product must not become a particle source itself. Fraunhofer IPA tested the material’s particle emission under mechanical stress and certified it suitable for ISO Class 5 air cleanliness, the evidence to request wherever ISO Class 5 mats are specified. The material has also been tested to ISO 22196 for antimicrobial surfaces, measured static dissipative, and rated low slip risk wet and dry.
None of this makes a facility compliant on its own.
Planning reusable cleanroom matting into your strategy
1. Map real routes: how people, trolleys and materials actually move, not how the SOP says.
2. Find the crossings where lower-grade traffic enters higher-grade areas.
3. Control every carrier: specify cleanroom entrance mats for wheels as well as shoes.
4. Size for contact: make contamination control matting long enough for repeated full contact.
5. Validate and trend particle counts and monitoring data before and after changes.
Frequently asked questions
What most commonly causes cross-contamination between areas?
People and wheeled equipment moving between areas of different cleanliness. Footwear, wheels and carried items transfer particles and microorganisms across boundaries, so prevention focuses on zoning and transition areas.
Are washable cleanroom mats suitable for ISO Class 5 areas?
Only with evidence. Look for independent particle emission testing against ISO 14644-1. CC Matting’s polymeric material holds a Fraunhofer IPA certificate rating it suitable for ISO Class 5 air cleanliness; any mat should still be assessed within your CCS.
Is a polymeric mat a like-for-like sticky mat alternative?
It serves the same purpose by a different method. Instead of discarding adhesive sheets, the polymer surface is cleaned and reused. Cleaning frequency and agents should be defined in site SOPs.
Do contamination control mats work for trolleys?
They can, with enough contact. In CPC Laboratories testing, plastic trolley wheels rolled across 90 cm of CCM matting showed 90.1% average removal of particles larger than 5 µm under the study’s conditions.
Does contamination control flooring make a facility GMP compliant?
No. EU GMP Annex 1 expects a holistic contamination control strategy. Matting or flooring can support it at transition points, but its role, cleaning and monitoring must be documented and justified within that strategy.
Next step
If you are mapping transition points, the Quality & Efficacy Manual contains the full test reports behind these figures, and our reusable contamination control matting page covers sizing for foot and wheeled traffic. CC Matting is a contamination control mat supplier installing across Ireland and the UK, and a contamination control mat distributor worldwide. To review a specific doorway or airlock, talk to the CC Matting team.