HEALTHCARE FACILITY AIR QUALITY
Figure 4: An EOLIS Air Manager system.
items. Where the item that is being disinfected is classified as a medical device, then the disinfectant is also required to carry a medical CE mark. However, these surface treatment devices, while killing microbes and thus stopping them getting into the air, are not themselves carrying out ‘air disinfection’. Total room decontamination tends to be put into the hands of strong oxidising agents in the form of hydrogen peroxide or ozone. These chemicals have strong microbicidal activity, but themselves break down quickly into harmless molecules relatively, leaving no noxious residues. There are useful devices, such as the Airinspace Cube Air, which can remove the disinfectant residues quickly at the end of the required dwell time, and can also be used for clearing the air of other sources of odours (including peracetic acid in endoscopy suites).
Ozone disinfection efficacy When considering different systems, both efficacy and safety need to be considered, and there is a wide range of choice on the market. When looking at the options of using ozone as a disinfectant, there are
Figure 6: The set-up and running of an ozone disinfection unit.
permissible safe levels in the normal air we breathe (on average over 8 hours less than 0.1 ppm or 100 μg/m3
), whereas
room disinfection levels will be looking at levels of maybe 5 ppm or more to kill the microbes, but these levels are immediately dangerous to humans. The disinfection efficacy of a system is dependent on a number of factors, including not only: 1) ozone concentration; 2) contact time with the microorganisms; 3) the inherent resistance of the targeted microorganism, but also 4) the relative humidity (RH) in the room, and 5) absence of by-products. Properly documented data are needed from the manufacturer to see how these aspects are each controlled for their system. On the RH point, a higher relative humidity allows for better reactivity of the ozone, and thus the dispensing system should be designed to adjust to the transient RH in a room.
With respect to by-products, on the safety side, it is important that the ozone is generated from oxygen from air where nitrogen is excluded from the process. This is to avoid the generation of nitrogen oxide gases at the same time. A side- effect of the action of ozone with organic compounds is the production of DBPs (disinfection by-products), which include
Barend ter Haar
Figure 5: A system for clearing chemical residues or contaminants from the air.
Dr Barend ter Haar, BSc, DPhil, is currently semi-retired, but has been involved in creating international and European standards in decontamination for many years, and has contributed to MHRA and British Healthcare Trades Association publications is this arena. He lectures around the world on various subjects, including decontamination and assistive technology. Originally a biochemist and research scientist, then involved in scientific and medical publishing, in more recent years his activities have been in the commercial world – as director of BIOtAK Ltd, an innovative enzyme-based process indicator company, Healthcare Innovations Australia, and BES Healthcare, a company oriented around consultancy towards best practices in decontamination and in assistive technology.
October 2021 Health Estate Journal 91
particulate matter. Ideally the system should therefore include a means to trap and collect these particles during and at the end of the cycle. The Danish Sterisafe Pro is a good example of a device that carries such safety features.
In conclusion
There has been an explosion of offerings of different technologies on the market over the last year on the back of the COVID-19 pandemic. Unfortunately you do not necessarily get what you pay for. There are some effective simple solutions for simple environments that need not cost more than a few hundred pounds a room, while there are others at much higher prices that have not been through strict efficacy and safety checks. Different environments do require different solutions. A new website,
www.cleanourair.co.uk, offers straight- forward basic advice as to a number of best practice safe and tested approaches. Alternatively, contact Bristol-based BES Healthcare, and the company will put you into contact with someone who would be pleased to talk through many of the available approaches to air decontamination, whether it is for disinfection, allergen removal, or pollutant destruction.
hej
©NatéoSanté ©Airinspace
©Sterisafe
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