On behalf of Julian Chen and Philip Wray
This article concerns an update following the installation of Radic8 air-cleaning units. They were bought direct from the UK suppliers at the beginning of the lockdown, with 10% discount for dentists. They are now only supplied by Schein and the cost has risen by £500. Blatant profiteering.
Four units have been installed at New Street Dental Care in Andover; one in each surgery and one in the waiting room. They are being run all day usually at full power level 3. They are not noisy. Calculations on our own rooms and reception shows that the air is filtered between 5 (reception) and 12 (my surgery) times each hour. Scientific results (from the manufacturers and other web sites) show between 96.3% and 99.4% bacterial removal from the air. From the same studies ‘The Radic8 technology range has a certified destruction rate of all respiratory viruses of 99.9999% on a single air exchange.@
How can we know they do what they are supposed to?
The practice has purchased portable atmospheric particle monitors; these are about £125 from Amazon http://humatech.co.kr/bbs/content.php?co_id=e_cont_020202 – Huma-i Advanced Portable Air Quality Monitor Indoor and Outdoor Measures CO2, VOC, Particle Matter (PM2.5 and PM10) Temperature and Humidity HI-150. If these are placed beside the outlet of the Radic8, we are pleased to find that the Particle Matter 2.5, and Particle Matter 10, are both zero, as hoped for.
When I place the monitor behind me, as far away as possible from the unit, it normally reads only between 4 for the ultra-fine dust and 10 for fine dust. It does of course not measure the presence of virus particles but gives a good idea of the air quality. This is good quality air.
|Unit of measure||Good||Moderate||Poor||Unhealthy|
|ppm (mg/㎥)||VOC||0.000 ~ 0.220||0.221 ~ 0.660||0.661 ~ 2.200||2.201 ~ 10.000|
(400 ~ 700)
(701 ~ 1,000)
(1,001 ~ 2,000)
(2,001 ~ 10,000)
For example, as soon as a denture is adjusted in the room, the fine particles rise to 60 and ultrafine to 15. With an AGP, with rubber dam and FFP3 protection, again there is a rise but to 20 to fine particles and 8 for ultra-fine. However, within 5 minutes the levels are back to the baseline, so I conclude that the air is being cleaned efficiently. It also rose with the Kalzinol powder being dispensed but again returned to low level quickly.
What has been interesting is the high levels of Volatile Organic Compounds, usually in the 0.68 (poor) range. In considering why, there are alcohol-based wipes in the surgery, there are impression-tray adhesives and the surgery room itself is less than 6 months old. Perhaps there are chemicals coming off the upholstery etc – I don’t know but we can only get this level down by full window opening. It’s also quite high in the other older rooms. The level also rose when dispensing the Kalzinol liquid -dangerous stuff Kalzinol!!
I haven’t assessed the CO2 ppm in the air yet, but I suspect a better reflection will be to use the pulse oximeter from our emergency drug kit before a dental procedure and again afterwards to assess blood oxygen levels. This will be tried next week.
So, in conclusion, the practice has evidence that the Radic8 units function as promised. We assume that bacteria and virus particles are being removed by ‘sterilisation chamber,’ which includes HEPA filters, 8 UVC lamps and a TiO2 mesh. The results on the web show an apparent 99.9999% kill rate in a single pass. ‘The forced airflow will greatly reduce surface settlement of viruses and therefore reduce the viral load on the surfaces. Radic8 technology does not actively kill viruses on surfaces but it does reduce the amount that can settle on the surfaces by destroying them while they are still in the air. ‘
We think they are an adjunct to our patient journey and make dentistry safer for ourselves.
Know who is attending
Contact the night before
Stay in the car until called.
Temperature and sanitise hands on arrival
Straight into surgery and close the door
Staff with appropriate PPE
Avoidance of patient to patient contact in common areas
One-way system upon departure
So, what evidence is there for declaring a 60 -minute fallow time? No-one can say. Is it the duration of the AGP, with water, without water, size and height of the room, airflow, etc. Just so many variables. We have many more detailed calculations on air cleaning based on room size, unit etc. Each dentist could do this as well and confirm the appropriate fallow time. It is also worth reading the letter sent by the British Association of Private Dentistry to Public Health England on 18th June 2020 discussing this issue
I feel with all these measures in place, working in a dental practice is safer than supermarket shopping!