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Environmental deep-cleaning and decontamination are crucial to the prevention and control of infection within confined areas, such as hospital wards and rooms within healthcare facilities, where instruments are routinely disinfected. Pathogens can easily spread from infected patients and staff through cross-contamination and it is possible for them to survive on equipment and surfaces for hours or days at a time.

Peracetic acid decontamination procedures are essential for the disinfection of these rooms and equipment to help infection prevention and control.  However, concerns over background levels of this sterilant used to disinfect is on the increase.  This high strength oxidant is dangerous to all living cells, so how can it be proven that no toxic gases remain, eliminating serious health risks of keyworkers and patients?


The international outbreak of Mycobacterium chimera amongst LivaNova 3T heater-coolers in 2015 saw a spotlight shine upon medical device disinfection and perfusion, with the implementation of peracetic acid for disinfection of the devices subsequently introduced.

However, since then, little regard has been given to the practical implementation of PAA in hospital settings. Advice on safe handling, ventilation and PPE is scarce, leaving questions about the health and safety of the staff disinfecting these devices, along with the long term, adverse health effects, becoming a cause for concern. 

PAA was introduced into decontamination due to its efficacy in preventing the growth of Mycobacterium species, whilst also being environmentally friendly. Its high reactivity, however, puts employees immediately exposed to it at risk, due to its corrosive properties, can cause severe chemical burns. Its vapours can lead to irritation of the eyes and mucous membranes of the respiratory tract, along with lacrimation and a pungent odour causing discomfort. Exposure to lethal concentrations of PAA results in haemorrhage, oedema and consolidation of the lungs.   However, despite all of this, there are currently no guidelines issued by providers of PAA for safe exposure limits to the vapours in the UK, or guidance for best practice for use and storage.

Some cases have been outlined in the literature of PAA causing hypersensitisation, occupational asthma and irritant vocal cord dysfunction.  One case which was brought to the attention of the HSE was a 48-year old male that was diagnosed with occupational asthma, after exposure to unknown concentrations of PAA vapours during the cleaning of endoscopes within a ventilated room. Protective clothing, gloves, goggles and a mask (not fitted with a vapour filter) were used. After five months he presented with rhinorrhoea, continuous cough and breathlessness with recovery of symptoms upon cessation of exposure.

Newcastle’s Freeman Hospital (NFH) has since written a white paper, following the completion of their study carried out within their medical facilities, monitoring PAA levels every 10 seconds with a portable leak detector, donated free of charge for the trial.  The trial investigated the obvious background levels of PAA whilst cleaning the heater/cooler system and storage of the sterilant. but proved that without the ability to monitor it, there could be no conclusion as to its safety or efficacy, just hypothesis

White Paper

Earlier this year, as part of ATi UK’s research into the use of peracetic acid as a sterilant and the dangers of not knowing what levels were present at any time, Director of Business Development, Tristen Preger, met with the Health and Safety Executive (HSE).  This highlighted a general lack of knowledge within the medical industry surrounding the measurement of such a strong disinfectant in the gaseous stage. Although there are no known regulatory requirements from the UK government, unlike the USA, the HSE states that ‘The Control of Substances Hazardous to Health Regulations 2002 (COSHH) requires employers to prevent or control exposure to hazardous substances. Where exposure cannot be prevented, employers are required to assess the risk to health, and provide adequate control measures when using hazardous chemicals.’ 

Unfortunately, the growing pressure on hospitals for the ‘quick turnaround’ of decontamination processes has led to cases where the health and safety of staff and patients has been compromised due to poor PAA monitoring, resulting in serious consequences.  HSE investigations found that the decontamination processes failed to protect staff sufficiently. Trusts using equipment that failed to monitor toxic gas levels were subjected to successful claims by staff for compensation. It is now widely believed in the industry that under COSHH legislation, where toxic gas vapour can be present, there now needs to be protection for staff who work in and around such areas.

Following on from this, NFH contacted ATi UK, specialists in analytical sensor monitoring solutions for gas and water applications, as part of its investigation into the value of continuous monitoring of background levels of peracetic acid, used within their Perfusion department for disinfecting their ‘heater cooler’ systems. This procedure has become common practice due to the potential of bacteria spread in this type of environment. The peracetic acid used is of a high strength and is required to be contained in chemical cupboard storage.

Due to their keen interest and knowledge within this field, ATi UK were eager to assist the hospital and donated a portable, continuous test system that measures constant levels of peracetic acid whilst logging the data.  The D16 PortaSens lll was used by NFH to carry out investigations into the background levels within the working areas, whilst also being used to detect any leaks of seals within the chemical storage cabinet. The data from the portable gas detector during a series of sterilisation processes, revealed that levels exceeded > 1 PPM  even after the process had been complete.  This demonstrated that potentially lethal levels of PAA could be inhaled by staff and stakeholders nearby, establishing that continuous monitoring is needed throughout decontamination processes.

By implementing continuous monitoring to check the background levels of PAA, the data could be used to prove when staff were safe to re-enter with the extraction in place. However, for the hospitals operating without this knowledge, staff are at high risk by continuing to work in potentially hazardous environments as the dangers are unknown. The hospital and Trust are also at risk of mitigation from the effects of toxic gas poisoning, due to there being no continuous monitoring in place.

Newcastle Freeman Hospital pride themselves on prioritising the health and safety of their staff and patients and feel strongly that all hospitals need to investigate the background levels in their hospitals to allow for the correct PPE and on this basis, a white paper was produced.


A total of 42 disinfection cycles were recorded during the study, with an example of PAA exposure and extraction represented in the graph below. Here, PAA concentrations peaked at 0.16ppm during a routine disinfection; this peak occurred during decanting of the concentrated Puristeril 340 and slowly declined as the ventilation system extracted it.

Graph – Extraction of PAA vapours during routine disinfection. PAA vapours peaked at a maximum of 0.16ppm during decanting and measuring concentrated of PAA, after which the ventilation system extracted the remaining vapours over a period of 5 minutes.

Paul Hill, Newcastle Upon Tyne Hospitals NHS Foundation Trust, said: “In my personal opinion a portable monitor should be considered an essential part of everybody`s cleaning protocol when using PAA to clean equipment. We strongly recommend the ATI uk portable monitor as it proved to be perfect for the task.

“It would seem our exposure levels are well below recommended standards, with peaks at expected times, however we have always been very proactive here at freeman. Without an across the board standard procedure for those units using PAA to clean heater/coolers, some units may be unknowingly unsafe in their practice. Therefore, we strongly recommend that every unit performs an audit of their practice like we have done.” 

Monitoring Peracetic Acid Levels

Peracetic, or peroxyacetic, acid is an organic compound that is characterised by a very rapid action against all micro-organisms. Areas within medical facilities use equipment that requires continuous sterilisation, such as perfusion and endoscopy re-processing, due to its effectiveness in killing bacteria and microbes.  Used in these environments, it will destabilise any molecule it can react with, such as those that make up microorganisms.

Any spillage of peracetic acid is a serious incident and hospital procedures require staff to immediately leave the room and call the fire brigade, but the cost of this is several thousands of pounds. Staff who work in these areas should have the appropriate protection, along with the correct equipment to measure background levels of the toxic vapour that comes off chemicals such as peracetic acid, hydrogen peroxide, chlorine dioxide and even strong bleach, as the high levels used in confined spaces can be dangerous if not extracted properly.

The only way to ensure the safety of staff working within these departments against this high strength oxidant is to monitor and alarm where levels exceed that of the exposure guidelines and must be monitored as part of Quality Controls Programmes.  This can be done with fixed or portable toxic gas detectors with specialist, reliable and accurate PAA sensors.  However, only two companies in the world make accurate sensors that can be used to protect staff, one of which is ATi UK. 

Monitoring chemicals such as peracetic acid enables you to effectively manage the breathing environment.  This continuous monitoring allows you to validate that the vapour in the air is safe and can also be used to demonstrate and prove that staff and patients are at no risk in these potentially hazardous areas.

Medical instruments, including endoscopes, can be sterilised multiple times a day at higher levels of PAA than ever before.  The increase in usage of re-processing cabinets can lead to issues created from wear and tear on sterilisers and re-processors, increasing the risk to those working closely to them. It is therefore essential to understand and monitor PAA vapour levels.

Protecting Lives and Preventing Legal Action

The high reactivity of PAA that underlies its benefits also means that excessive exposure to the vapour can be harmful and can cause serious health issues, including:

  • Permanent damage to lungs
  • Permanent damage to eyes/sight
  • Pulmonary edema
  • Burns to skin
  • Damage to ‘mucous membranes’

Unfortunately, the pressure on hospitals for the ‘quick turnaround’ of decontamination processes has led to cases where the health and safety of staff has been compromised due to poor PAA monitoring, resulting in serious consequences.  In these cases, HSE investigations found that the decontamination processes failed to protect staff sufficiently. Trusts using equipment that failed to monitor toxic gas levels were subjected to successful claims for compensation.


The research conducted by NFH demonstrates the urgent need for a review of PAA monitoring standards to ensure that all departments using strong sterilant, including storage and equipment containing sterilant, monitor the background levels of the toxic gases used to ensure staff safety.   It also proved that although the smell of acetic acid within the PAA solution was present, without the ability to monitor time-weighted average and spikes in readings when spilled, there could be no conclusion as to the level of safety within the areas where monitoring took place. 

Jacob Garthwaite, Perfusionist – Freeman Hospital, Newcastle believes an urgent review of standards is required across the UK: “ATI’s PortaSens was vital in the validation of our ventilation system during the cleaning of LivaNova 3T Heater/Coolers. We were able to effectively assess peracetic acid (PAA) vapours in real-time, informing technicians of any leaks or spills that might cause the environment to become unsafe. The findings of our validation prove that our ventilation system provides a safe environment, below EPA time-weighted average guideline levels, for PAA during routine cleaning and small dilute spills. Furthermore, the PortaSens provides peace of mind in providing a finite figure regarding staff safety as well as a threshold for evacuation. I would strongly recommend that any centre carrying out cleaning of 3T Heater/Coolers using Puristeril 340 or other PAA disinfectants validate their working environment with such a gas monitor.”

Under COSHH legislation, employers need to prove a health condition has not been due to exposed levels of toxic chemicals, but without the monitoring of background levels this cannot be done and can result in costly legal action. However, if a member of staff complains of a condition that is often caused by over exposure to high levels of gas vapour, logged data from the monitoring process can be used to demonstrate that the area remains safe.

The results of the white paper corroborate the urgent need to regularly audit perfusion areas where PAA is used and stored with the PortaSens lll gas detector, used within the study. The application of ATi’s PAA sensors in decontamination equipment is a prime example of the way in which monitoring data is crucially important to the success of a measure, whilst helping to protect and save lives.  ATi’s PharmaSafe range of gas monitoring solutions significantly improve the effectiveness of the decontamination process, helping to keep key workers and members of the community safe.

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