How Clean Is Your Cleanroom Sock?

tamsinmarshall4
Jul 9
3 min read

Updated: Jul 14

Opinion Article | Open Access | Published 11th of July 2025

How Clean Is Your Cleanroom Sock?

Charlotte Johnson, BSC(Hons), Marta Underwood, (BSC), Micronclean

EJPPS | 302 (2025) https://doi.org/10.37521/ejpps30216

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Introduction

With the publication of the revised EU GMP Annex 1, the requirement for personnel to wear cleanroom-specific socks prior to entering Grade B to C change rooms has become explicit. This development elevates the status of what was once considered a minor or even overlooked garment in contamination control protocols.

In response, Micronclean has introduced a reusable, laundered cleanroom sock, designed to meet both regulatory compliance and sustainability objectives. However, despite its technical merits some hesitation remains in the marketplace.

To establish a data-driven foundation for informed decision-making, Micronclean conducted a controlled comparative study assessing the microbial cleanliness of its laundered cleanroom socks in comparison to commonly available domestic polycotton socks.

Methodology

The study compared two sock types:

A commercially available polycotton domestic sock (Domestic Sock)
The Micronclean Reusable Cleanroom Sock (Cleanroom Sock), made from 100% synthetic fibres and designed specifically for cleanroom environments

Both sock types were worn for a standard 8-hour working shift by participants across a range of cleanroom grades and demographic backgrounds, which ensured a minimum sample size of 6 socks per dataset .

After use, each sock was subjected to one of the following laundering protocols:

Domestic wash at 30°C followed by domestic tumble drying
Domestic wash at 60°C followed by domestic tumble drying
Micronclean’s validated cleanroom laundering process, comprising thermal disinfection and HEPA-filtered tumble drying

Following laundering, microbial bioburden testing was conducted in accordance with BS EN ISO 11737-1:2018 to evaluate the efficacy of each cleaning method and compare the relative cleanliness of the sock types.

Results

Process	Sock Type	Bacteria (CFU)	Fungi (CFU)
Domestic 30°C Tumble Dry	Domestic Sock	TNTC	TNTC
	Cleanroom Sock	TNTC	TNTC
Domestic 60°C Tumble Dry	Domestic Sock	TNTC	TNTC
	Cleanroom Sock	TNTC	TNTC
Validated Cleanroom Process	Domestic Sock	129	0
	Micronclean Sock	9	0
TNTC = Too Numerous To Count

Figure 1. Domestic sock, Domestic 60°C washing and domestic drying process. — **Figure 1.** Domestic sock, Domestic 60°C washing and domestic drying process.

Figure 2. Micronclean cleanroom sock. Micronclean cleanroom laundry process. — **Figure 2.** Micronclean cleanroom sock. Micronclean cleanroom laundry process.

The findings demonstrated a clear hierarchy in both washing process efficacy and sock material suitability:

Domestic laundering, even at elevated temperatures (60°C), was insufficient to reduce the microbial bioburden of either sock type to a level that could be counted.
The Cleanroom Sock, when processed through the validated cleanroom laundering cycle, exhibited consistently low microbial bioburden.
The Domestic Sock, even when laundered via the validated cleanroom process, retained statistically significant higher levels of bioburden than the Cleanroom Sock, highlighting the influence of textile composition on decontamination outcomes.

Discussion

These results affirm that laundering methodology alone is not sufficient to achieve a low microbial bioburden; fabric type plays a critical role in microbial retention and release.

In addition to performance advantages, the reusability of Micronclean’s cleanroom socks offers environmental and economic benefits by reducing single-use waste streams, without compromising cleanliness or regulatory compliance.

Conclusion

Micronclean’s laundered cleanroom socks offer a robust solution for facilities aiming to align with EU GMP Annex 1 and improve sustainability in their contamination control practices. The study supports the following conclusions:

The Micronclean Reusable Cleanroom Sock, when laundered via a validated process, achieves superior microbial cleanliness compared to both domestic socks and domestic laundering protocols.
The Micronclean Reusable Cleanroom Sock represents a compliant, sustainable, and operationally sound alternative to single-use or inappropriately laundered options.