Low temperature disinfection

10 April 2020

Disnfection has to be top of every operator’s list at the moment as we battle to contain the Covid-19 pandemic, but don’t forget other nasty pathogens that also need to be eliminated. Richard Neale has some useful advice to offer

The understandable fear of a pandemic following the recent outbreak of disease caused by the new coronavirus Covid-19 has raised questions regarding the efficacy of some laundry processes in several areas. Not every organisation has been affected – a great many are delivering superb service with others rethinking their infection control protocols. This month we consider the potential risks which only the launderer can control effectively in each of the hospitality, cruise liner and care home sectors. We look at how infection controls could be implemented, while maintaining the low carbon footprint which the transition to low temperature washing can deliver. It is assumed that readers will already have instituted the management and staff actions detailed in the updated online March 2020 issue of LCN (pages 31-33 https://secure.viewer.zmags. com/publication/64666be7#/64666be7/30) and they are not repeated here.

The challenge

Members of the general public, our ultimate customers, require textiles which are not only visibly but also hygienically clean. Leading health authorities require a reduction in bacterial contamination of 5 log10 to meet their minimum requirement for disinfection, which means that a fouled sheet coming in with an average of say 10,000,000 bugs per square cm must have this reduced to no more than 100 per sq cm after laundering. This is not sterile, but the reduction makes it quite adequate for the human body to cope with in most cases. The sheet would be deemed clean and disinfected to NHS standards and similar standards are used throughout the world.

Recent work pioneered by The Guild of Cleaners and Launderers3 and sponsored by The Worshipful Company of Launderers and others, in conjunction with the University of Northumbria, has shown that a laundry process with a main wash temperature of say 40C does not necessarily achieve much disinfection. The textiles may well come out looking and smelling clean, but they would not meet any recognised disinfection standard. This result has taken on a greatly enhanced significance with the recent worldwide spread of coronavirus Covid-19. As an industry we should look to the challenge of low-temperature disinfection and in this issue of LCN, we look at the issue and suggest some initial actions in three sectors:

a. launderers serving the cruise liner market (in which the UK is heavily involved),

b. care home laundries, catering to the needs of elderly residents in confined premises,

c. launderers serving the hospitality market, involving restaurants and hotels.

Bugs which are difficult to kill

Norovirus, as its name implies, is a virus rather than a bacterium. For this reason, many standard hand gels are not adequately effective against Norovirus. To destroy it completely requires a laundry process, or a hand gel, which has good virucidal properties – that is it actually destroys the virus. It tends to come into the body orally, from contaminated hands, food and drink. Patients may require treatment for dehydration, but there is no vaccine or curative medication.

There are laundry processes available across Europe which will deal with Norovirus. One process achieves the desired log kill at only 40C; others require 60C or more. Certified processes are available, built around peracetic acid, in which the hydrogen peroxide component appears to degrade the surface of the outer membrane, allowing the acid radical then to get inside and degrade the virus itself. Concentrations of the various ingredients are critical, as are the process conditions, but they have been shown to work. Whichever process is chosen should be validated regularly.

Clostridium difficile (C. dif.) is known to be a spore-forming bacterium and the spore-form is not killed by implied thermal disinfection (in a main wash involving 3 minutes plus mixing time at 71C). Traditional processes have been based more on dilution than destruction, although it is more vulnerable when in the vegetative state. Recent research in 20191 compared five laundry processes, variously involving an alkaline detergent, sodium hypochlorite, hydrogen peroxide and peracetic acid. The work concluded that although sodium hypochlorite does have some sporicidal effect on C. dif., it does not provide an adequate basis for a disinfecting process. The most encouraging result for the high-volume textile rental market was the identification of a tunnel washer process based on peracetic acid which, with the right processing conditions, would cumulatively render textiles essentially free of C.dif. contamination. Adoption of this would still need regular validation.

Bacillus cereus is another spore former which poses the same problems as C. dif. and which is being tackled in a similar manner.

Covid-19, SARS and MERS are particular members of the coronavirus family, as is the common cold. They are dangerous because they are so virulent and are passed readily from one person to another, with fatality rates which vary. There is evidence to suggest that Covid-19 may not be killed by implied thermal disinfection at 71C for 3 minutes plus mixing time and that it may require 10 minutes at 90C or 15 minutes at 85C. As an alternative, leading detergent suppliers can offer thermo-chemical alternatives which have shown to be effective against Covid-19 at lower temperatures. Providing one of these techniques is correctly adopted and validated, after liaison and consultation with your detergent supplier, there should be few issues for the professional launderer.

Chemical disinfection

Thirty years ago, oxidation was the prime means of chemical disinfection, using either sodium hypochlorite in the first rinse or hydrogen peroxide in the main wash, with the former being generally more effective. This is now giving way to processes based on peracetic acid which, under the right conditions, offers longer service life for cotton-based textiles and less impact on the environment.


The advice given this month is designed to be read in conjunction with the updated online version of that given last month. The current challenge with Covid-19 is not going to disappear quickly, but it has given an incentive to getting assured disinfection with validated outcomes (with regard to both viruses and bacteria) built into the business model of every rental laundry, care home and cruise liner. Please address any queries to the editor of LCN at

E: kathy.bowry@laundryandcleaningnews.com.


1. Cruise lines may well face outbreaks of both Norovirus and Covid-19 in the future, so you should ask your chemicals supplier, now, for processes which will control these viruses. You need a modern system for this, together with the official validation and certification, in line with your own procedures, targets and Risk Assessment.

2. You should ask your chemicals supplier for disinfection checks on each of your machines. These should be based on pre-infected swabs or DES2 controllers, both of which your supplier should be familiar with.

3. Following these recommendations will provide a robust response to any infection control queries, regarding the laundry, at your ports of call.


1. Care homes could expect outbreaks of Norovirus and Covid-19 during this year, so you should be asking your supplier, now, for processes which address these difficult to kill viruses.

2. If you are washing without a validated technique, then you should immediately contact your supplier for guidance. Your supplier should be able to give advice on a modified low-temperature process which gives thermo-chemical disinfection, together with official certification for effectiveness against the more challenging micro-organisms.

3. You may wish to get an annual check on your disinfection with respect to bacteria, using either pre-infected swabs or a DES2 controller, with results which you can keep with your health and safety records to demonstrate the effectiveness of your processing.

4. You may want to augment this with a periodic in-house check and monitoring system. LTC can provide further information on this.

5. If you keep a documented record of each of your checks, this will provide a robust response in the event of any investigation or query, especially one following an infection outbreak.


1. There is an increased potential for linen infected with Covid-19 during this year, so you should be asking your supplier, now, for a certified process which deals with this virus and its ability to survive in the environment.

2. Check with your chemicals’ supplier that all the processes you are using are giving disinfection which deals with bacteria and potentially with Covid-19.

3. Those laundries using a certified process for low-temperature, chemical disinfection, should ask for and keep on file a copy of the certification and ensure that the process is regularly validated.

4. You should consider implementing the requirements of the European Norm for assured disinfection – EN14065. These are not that onerous and will provide a useful professional and management tool.


1. Association of Professionals in Infection Control and Epidemiology, Inc. (2019).

2. DES (Di-Ethyl-Stilbestrol) controllers are pre-infected sealed swatches which enable the safe and rapid determination of the log reduction in microbial contamination actually achieved in the target wash process. They are purchased from an independent laboratory, washed once and then returned for laboratory analysis.

3. The Guild of Cleaners and Launderers (2020).

SPECIAL PROCESS: Norovirus is not easily destroyed and needs a special laundry process
BROKEN DOWN: Clostridium difficile forms a protective spore and this must be broken down chemically in order to destroy it

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