UV-C disinfection is a technology that has been used for decades to remove bacteria from water, surfaces and air. Its good biological effectiveness against bacteria, fungi, yeasts and viruses is well proven – but the risks to humans are also well known. How can this method be used as an additional kind of disinfection in commercial laundries? What are the best places and purposes to choose for its application? What measures need to be taken to protect workers? Here we give answers to some of the main questions.

Biologically highly effective: that's how UV-C disinfection works

Ultraviolet ("UV") radiation is invisible to humans. It is optical radiation in the short-wave electromagnetic frequency spectrum – right next to the part of the visible light spectrum which the human eye perceives as the colour violet. UV radiation is divided into three ranges by wavelength: UV-A (400–315 nm), UV-B (315–280 nm) and UV-C radiation (280–100 nm).

Microorganisms that are exposed to UV-C radiation are irreversibly deactivated in anything from seconds to a few minutes. Most bacteria, with the exception of spores, are killed in about 2 minutes even in daylight.

It is because of this excellent biological effectiveness that disinfection using UV-C radiation is used alongside thermal and chemical disinfection, especially to purify drinking water and water for swimming pools, water for industrial processes and sewage water, before it is piped. Work surfaces in clean rooms, isolation facilities, for example in hospitals, and sterile workbenches are treated with UV-C light to kill bacteria. In principle, therefore, both aqueous media and hard surfaces can be microbially decontaminated using UV-C.

Use and benefits in laundries – technical and commercial aspects

When disinfecting with UV-C radiation, the general principle is: where there is any dirt or shadow, the radiation is not effective. Consequently only clean, smooth surfaces that are accessible to the radiation can be effectively treated. So in practice this always means 2 work processes: first, cleaning and then disinfecting. This is an aspect that needs to be taken into account by any company considering using this method – whether as a decontamination alternative for technical surfaces which have previously usually been cleaned by wiping with chemical disinfectants, or for container airlocks that are disinfected thermally.

The use of UV-C disinfection in HGV loading areas is currently the subject of scientific debate and trials. Until now, disinfecting has often been carried out by spraying or wiping. The aim of the research and development is to replace the spraying method, which is not ideal because of its health risks, the risk of explosion and its inadequate effectiveness. UV-C seems to be the method of choice here – but only if it can be proven safe and effective to use.

Health risks and workplace protection

UV radiation in all three frequency ranges, A, B and C, is carcinogenic and can cause skin cancer. This applies particularly to UV-B and to a lesser extent to UV-C radiation. Sunburn, for example, is a clear indication that someone has been exposed to too high a dose of dangerous UV radiation.

That is why the eyes and skin of employees must be protected when working in the presence of this radiation: that is enshrined in EU directive 2006/25/EC and has been implemented in German law since 2010.

A laundry owner is, therefore, like any employer, obliged to measure, calculate and evaluate the UV radiation to which the employees in their company are exposed. This has to be carried out at appropriate intervals and by qualified people or organisations. The data that is collected must also be saved in such a way that it can be viewed at a later date.

On the basis of the information obtained in this way, the employer is then obliged to take measures to limit or avoid UV exposure in order to keep within the legal limits. For UV-A, -B and -C radiation, that maximum radiation dose is _Heff = 30 J/m² over a period of 8 hours, i.e. over a working day.

Special protective measures in laundries

In principle in the laundry industry, a distinction needs to be made between two places where UV-C disinfection systems could be installed and operated: in "enclosed" systems on one hand and "open" systems on the other.

Fully encapsulated or enclosed systems would include, for example, an HGV loading area or the airlocks on laundry containers. Those are areas where no-one is present while the system is operating and from which no UV-C radiation can escape. Here, the workplace protection requirements are met and there is no risk to laundry workers. Incidentally, even where enclosed systems have viewing windows made of normal glass, there is no risk because conventional glass is impermeable to UV-C radiation.

Open systems, where people are present while they are operating and so could be affected by the UV-C radiation, include the pressing area or the laundry sorting conveyor belts. Here, measures must be taken to protect workers. In an ideal situation, that would mean further enclosing the UV-C lamps as completely as possible. Where that is not possible, employees must be provided with appropriate non-UV-C-permeable protective clothing and goggles.

In practice, as a rule of thumb for open systems, the following applies: if you cannot see the beam of the UV-C lamp, everything is OK. If you can see the lamp shining – be that directly or as a reflection! – then eyes and skin must be appropriately protected with non-UV-C-permeable goggles and UV-C-proof clothing.

Conclusion

UV-C is a sensible option for commercial laundries because of its proven good biological effectiveness in practice. Where and how the technology is best used in individual companies can only be determined by taking account of the specific balance of technical and commercial factors in each case.

Factors to be considered include the suitability of the premises or surfaces, including the required cleaning work, the installation costs for the UV-C equipment, whether it can be efficiently supplemented with other decontamination methods, the number of employees in the company and therefore the cost of the necessary workplace protection measures. These considerations of the costs and benefits should also include risk management in the event of any harm being caused.