Introducing Decon Pete who will discuss everything dental practices need to know about disinfection and decontamination. In his first column, Pete discusses ACH and its importance to dentistry.
Who would ever have imagined as we were all singing Auld Lang Syne at the end of 2019, welcoming in a new year, that 2020 would be one consisting of a global COVID-19 pandemic?
The UK went into a national lockdown with all but essential business’s remaining open.
When the country, eventually, began to re-open dentistry was met with a new set of protocols and a new way of working.
Dentistry was already one of the safest divisions of the medical industry and its professionalism quickly adapted to implement and enhance these working procedures in order to make it even safer for its patients and staff.
We have seen new working documents from the NHS SOPs and FGDP’s COVID-19 Practical Guide, to the industry trade support in aiding these implementations.
Infection control has become even more important with the day to day running of the clinics. Along with this we have seen an increase in the fallow time.
There are many aspects of the current procedural documents, that I aim to discuss in these articles.
I want to start with air changes per hour (ACH), which is an area that I receive a lot of questions for help and support about.
What is ACH?
ACH is incredibly important. It aids the effective removal of aerosol and replenishes with fresh air.
Aerosol generating procedures we describe as: ‘Medical procedures that have been reported to be aerosol generating and consistently associated with an increased risk of pathogen transmission.’ (WHO, 2014)
We also naturally produce aerosol from speaking, breathing, coughing and sneezing. All of which could become a potential mode for transmission of COVID-19.
What type of ventilation do I need?
There is a lot of guidance around this, which can sometimes get confusing when trying to make a choice. The main types of ventilation are as follows: natural, mechanical (negative, positive, supply and extract) and scrubbers or conditioners.
Natural ventilation is a window or door, which will allow fresh air to mix with the room air and help to dilute aerosol. However, these cannot contribute to ACH due to there being no way of quantifying the level of dilution.
Mechanical ventilation breaks down into three areas.
Negative pressure means extracting air from the room. This is ideal for areas such as clinical areas.
Positive pressure means drawing air into the room. This is ideal for areas such as operating theatres.
Supply and extract means drawing clean air into the room and extracting it out. This is ideal for decontamination rooms or LDUs.
Air conditioners/scrubbers do not provide a room with fresh air. Instead they recirculate the existing air and remove or dilute any aerosol contaminants.
It is important to remember that these units are only effective if positioned correctly within the surgery. Ideally, place them as close to the source of aerosol production as possible. And not positioned behind the operator or nurse.
The effectiveness of these units will all depend on its air flow rate. The manufacturer can advise on this.
These units prove effective when other means of alternative environmental mitigation are not feasible or practical. You should always consult with the manufacturer when making a choice.
Once you have chosen your type of ventilation, you will then need to make some calculations. These calculations will consider areas, such as the size of the room, number of people and temperature.
You will require all these factors to ensure you install the correct ventilation. Particularly when trying to achieve the desired ACH.
Whatever you choose it is important to always obtain the advice of an air filtration specialist who can assist you in deciding.
For further guidance you should also refer to BS 5925 : 1991, HTM03-01, HTM01-05, SDCEP and FGDP.
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