Under the regulatory spotlight: whole room decontamination

CLEANING AND hygiene are imperative to prevent the potential survival and spread of microorganisms. This is especially pertinent for cleanrooms and other settings that must remain sterile, such as healthcare or food preparation areas. In these environments, whole room disinfection is an ideal process because it enables difficult to reach places to be thoroughly disinfected.  

Two decontamination techniques commonly employed are ultraviolet (UV) light systems and automated chemical misting (airborne automated disinfection systems), popularly known as ‘fogging machines.’ There have been regulatory changes concerning both of these recently, so any facility employing the use of one of these systems should ensure that they are aware of the changes now in effect and whether their system is fit for use under the new guidance.

Clearing the fog

BS EN 17272:2020 is the required method for all automated airborne chemical disinfection systems for both small and large enclosures in the EU and UK. Whilst its predecessor (French standard NFT 72-281) focussed on the bacterial activity of a system and only demonstrated the surface effect of the chemical, the EN 17272 standard is much more comprehensive. 

It is formed of two parts. 

• Part one: focusses on efficacy, ensuring that the minimum microorganism reduction requirements are met for each claimed activity and for the targeted application area. It also details the testing and requirements to show its effect on a broader spectrum of organisms including bacteria, yeast, mould, spores, and viruses.
• Part two: examines distribution: the product must demonstrate that it has been effectively distributed within a space. This means that automated airborne disinfection systems must be able to disperse the product to all four corners of the test chamber, whilst still demonstrating a significant level of efficacy against organisms shadowed from the source of the fogged disinfectant. 

This additional requirement has added a significant level of difficulty to the test, meaning that many pieces of equipment may no longer be compliant with the latest regulations, and could effectively be removed from the market if they do not suitably distribute the product to maintain a claim. 

Whilst this is obviously disadvantageous for some systems and manufacturers, it adds a level of confidence that the previous testing had overlooked. When sanitising a sterile work area containing equipment or furniture, demonstrating that a product can effectively produce results on surfaces shadowed or obscured from the fogging device is vital to reducing the risk of contamination.

Beyond the new requirement for distribution, the testing offers claim flexibility that allows machine and product combinations to prove suitable effectiveness for a range of areas of use, for example, broken down bacterial claim requirements for the medical area, veterinary area and for domestic/industrial uses, as well claims for specific issues a facility may have. These all require log reductions, offering peace of mind that the system is suitably effective at sanitising against specific challenges, such as spores, mould, and viruses, which can pose a significant risk to any sterile environment manufacturing site. 

Since it was released in the height of the pandemic and due to the ongoing pressures that all companies have faced, this standard is still not widely used even though it is now a required test method. Both manufacturers and users should be aware of the test requirements of EN 17272 and how it can significantly change their products usage for both small enclosures and full room disinfection. 

UV under the spotlight 

Standard BS 8628:2022 was published in April last year and is now the required testing for ultraviolet light systems. Largely based on the existing airborne disinfection standard EN 17272, with some minor variations for UV devices, this new method standardises a distance for the emitter from a test surface, allowing for an assessment of power versus contact time for the UV unit. It covers the requirements and methodology for testing the efficacy of UV devices, determining bactericidal, mycobactericidal, sporicidal, yeasticidal, fungicidal, virucidal and phagocidal activities.

Previously, remote UV systems had no formal guidance on their effectiveness. The assumption of efficacy had been based on available research papers and in-house test methods of multiple testing laboratories or research facilities, which means that each different machine may have been tested in completely different ways – if it has undergone testing at all.  

Whilst UVC light is certainly harmful to microorganisms, there are many issues with assuming the effectiveness of an emitter based on publications rather than testing. These can include:

• ensuring the emitter is at a suitable distance to remain effective;
• whether the emitter has the same effect low to the floor as it does directly in front of it;
• whether the light sources are of a suitable power;
• how to prove if a device is effective against the organisms of interest to a specific facility. 

Unlike fogging devices, light sources have no requirements for the distribution of the product. Instead, the method evaluates the time taken to reliably cause a significant log reduction at a set distance from the test surface. The test surfaces are perpendicular to the light source to imitate some level of appropriate shadowing for flat surfaces in a facility. 

Standardising distances and organisms for testing allows for a clear evaluation of equipment and gives quantifiable results of effect. In contrast to the previous requirements of UV emitters, customers can easily compare systems’ required exposure times and ensure that the testing meets the internal requirements of any facility where these types of products are to be employed.  

Initial testing has shown that the assumptions for light exposure measurements, on which devices’ claims had previously been based, is not sufficient to base usage instruction because various factors can affect the efficacy of the light. Introducing interfering substances to represent surface soiling, surfaces not directly facing the emitter, and the requirement of a standard distance mean that former calculations of how much light is required to sanitise a surface effectively no longer apply. The new method now ensures that these products are tested in a way that better relates how they are used in the real world. As more machines undergo this testing, further design and usage changes may be implemented. 

Looking ahead

These methods have harmonised a market and added confidence for end users, however gaps remain. Some machines still have no test methods aimed at their use specifically. For example, there is currently no method to standardise the efficacy of products that aim to sanitise the air in a facility, and neither of the published methods are specifically designed for use with products like ozone or ionised air. These types of products may be effective in principle but such gaps in regulation and testing mean that there is still a requirement for in house or bespoke testing. 

These latest standards do give a solid foundation though, on which to base future methods. They lay out clear criteria for the disinfection of surfaces that products can be held account to. 

Businesses that operate in any sterile environments must be aware of the standards that are now in place, both to ensure a continued contamination free space and to stay compliant.

At MSL, we are at the forefront of industry changes – in fact, we worked closely with the CH/216 committee at The British Standards Institution to develop BS 8628:2022. At our purpose-built laboratory, which was specially commissioned for this process, we can test the efficacy of UV disinfection and automated fogging systems to the latest standards, helping to assure companies that the system employed at their facilities is both suitable for use and effective against the organisms that pose the greatest risks.

Peter Thistlethwaite is technical projects manager at MSL Solution Providers

For more information visit www.msl.io