Air purification in dentistry

air purificationMars Purifier explains how its air purification system is a reliable way to help increase efficiency in the dental practice.

Mars Purifier is the only UK-based company accredited to ISO 14464. Supporting documentation is supplied with the purifier, which users can submit as evidence during an inspection.

Dentistry and COVID-19

The world is currently faced with a threat to its health that has changed millions of lives forever – COVID-19.

Research has shown that COVID-19 is an airborne virus that is most adhesive to the oral mucosa and the upper respiratory system. Working directly in patients’ mouth exposes dentists to a higher threat than most professionals (Cevik et al, 2020).

As we try to regain a sense of normality, we must be thorough and pragmatic in our approach.

Throughout the year, there has been an introduction of new guidelines. At the time of this article (March 2021), the use of air purifiers/cleaners is among the environmental mitigation options supported by guidance from many relevant authorities (BDA, SDCEP, FGDP, PHE, SOP)

We must remember that the safety of patients and staff is paramount and cannot be left undetermined. There should not be any ambiguity regarding how dentistry should progress. There is a need for clarity and standardisation.

This article aims to provide clarification on Mars Purifer specifically and how to use it to benefit the dental profession.

Key terminology

  • Air purifier or air cleaner/scrubber – a device that removes contaminants from the air in a room to improve indoor air quality
  • PPE – personal protective equipment (varies on the procedure)
  • AGP – aerosol generating procedure – involves clinical procedures where airborne particles are created via highspeed drills and scalers
  • CADR – clean air delivery rate. This is the value to determine the ‘power’ that varies from purifier to purifier
  • Fallow time – the ‘settle down period’ after an AGP before clinicians can use the room again. Dependant on ACH = CADR/vol +/- mitigating factors
  • ACH – air changes per hour – the value associated with how many times the air in a room is cycled
  • UVC/UVGI – ultra violet germicidal irradiation
  • HEPA – high-efficiency particulate air.

Dentistry and air purification

In response to recent events, the interest in air purification solutions has risen substantially.

The impending eventual return to everyday life means something different in the field of dentistry. Dentistry expects to see more patients to relieve the backlog caused by the stagnation of care within the last year.

Most practices at the moment are in a delicate position of trying to meet NHS targets, maintaining a safe environment and ensuring the patients feel comfortable attending appointments.

Mars Purifier effectively solves all of these problems. It is the only ISO 14644 certified purification system available that falls in line with the current NHS/PHE/ SDCEP/FGDP guidelines.

Mars Purifiers are extremely quiet, which is something that clinicians often vastly overlook. When the air is at optimal quality, the device is almost silent.

Its sleek design looks fantastic in surgery or communal areas putting both patients and staff members at peace of mind and being aesthetically pleasing.

Calculate fallow time

The current guidance from Public Health England (PHE) and advice from the New and Emergency Respiratory Virus Threats Advisory Group (NERVTAG) allows a reduced fallow period in a treatment room with 10 ACH.

To ascertain the fallow time after a Group A procedure: use powered, high-velocity instruments that also emit or require water or irrigants for cooling.

These procedures will then produce aerosol particles <5μm and require airborne transmission-based precautions, procedural mitigation and fallow time.

You must consider four factors:

  1. What is the ventilation rate?
  2. Is high volume suction used?
  3. Are you using rubber dam?
  4. Is the Group A procedure >5min or <5min?

You can calculate the ventilation rate using this formula: ACH = CADR divided by the room volume. The ventilation rate is exactly half of this.

The CADR value that essentially measures each device’s effectiveness will differ from one another.

NSS SBAR (national services Scotland) recommend air cleaners effectiveness should be ‘downgraded’ to 50% of their manufacturers’ CADR (clean air delivery rate) output when calculating ACH. Mars Purifier achieves up to 1,280 CADR; it surpasses the safe practice margin.

Mars Purifier can offer a range of products carefully tailored to room size achieving ACH greater than 10. So you can minimise waiting time and maximise patient turnover, whilst not compromising on patient safety. For reference, a window open in an average surgery will supply one ACH.

In summary, using a purifier achieving air changes greater than 10 with no other mitigating factors, fallow time is 15 minutes, with the possibility of further reducing it to 10 minutes with either high volume suction and/or rubber dam.


HEPA filtration is the gold standard for air purification. This feature is arguably one of the most important to have in a purification system. Although generally HEPA 13 is acceptable, Mars Purifier is one of the very few sources of HEPA 14 commercially available.

  • H14 HEPA – effectively filters 99.995% of pollutants in the air. HEPA-14 filtration efficiency is 10 times higher than HEPA-13 filters and captures 0.1 microns
  • H13 HEPA – effectively captures 99.97% of harmful particles down to 0.1 – 0.3 tiny microns. Commonly referred to as ‘medical-grade air filtration.’ Mars Purifier provides this filter as standard in all ranges
  • H11 HEPA – only captures 95% greater than 0.3 microns, missing many of the concerning airborne particles. Many air purifiers in the market are H11
  • UVC filtration – this is a process that deactivates the membrane around a virus. After a high-risk procedure in hospital or surgery, we recommend a source of UVC filtration. Users can achieve this either with a separate device or, in the case of Mars Purifier, an inbuilt filter as part of a multi-stage filtration setup
  • Ion technology – releases silver ions repeatedly to eliminate bacteria effectively
  • Photocatalyst technology – has also been introduced in the higher end models that convert water in the air to modify harmful pollutants into less harmful ones. This is based on the principle that radiation of suitable wavelengths can be absorbed by many semiconductors, facilitating the creation of reactive oxygen species (ROS) that can decompose air pollutants (Hay et al, 2015)
  • Pre filter – captures large particles (hair, large dust particles) to extend the life of the air purifier
  • Activated carbon filter – carbon has a large surface area, which in this case helps capture air pollutants. Adsorption of the molecules occurs as organic compounds react chemically with the activated carbon.

Air purification and coronavirus

Coronavirus has a dimension of 0.12 microns. At current times coronavirus represents a global pandemic health issue and also a significant concern that makes us all think critically about indoor air quality.

The Centers for Disease Control recognises three main routes of transmission:

  1. Direct large droplet transmission between people within close proximity
  2. Indirect respiratory droplet deposition on surface and object
  3. Airborne transmission via small particles in aerosol containing the viable virus.

With this, we can therefore conclude that air purifiers lower the number of virus particles in an indoor space. This results in lower transmission rates (Nazarenko, 2020).


How often do you need to replace and clean the filter?

Clean the filter every three months; do this by opening the dust sensor’s cover plate and using a blower to blow out the dust in the sensor. Also, using a vacuum to absorb the large particles around the filter.

To maintain the best performance these purifiers provide, it is important to replace the filter at the right time. The change indicator light displays on the air purifier when the filter needs replacing. The recommended filter change: six months (4,380 hours) when used 24 hours a day.

How do I use it?

Have the device running on automatic mode throughout the day. Any harmful pollutants in the air will then automatically purify – indicated with an LED colour change and a rising value.

After an AGP, we also recommend to have the device on full power for the fallow time duration.

Does it produce harmful ozone because of the UVC technology?

No it doesn’t emit ozone – the reason for this is because you can only produce ozone below 200nm. At 253nm, the germicidal wavelength Mars Purifier uses does not generate ozone.

The ultraviolet germicidal irradiation UVC wavelength is therefore an invaluable tool for air purifiers. By leveraging germicidal energy to keep refrigeration coils free of microbial growth, promoting the benefit of reducing the spread of airborne infections.

For more information, visit


Cevik M, Kuppalli K, Kindrachuk J and Peiris M (2020) Virology, transmission, and pathogenesis of SARS-CoV-2. BMJ 371: m3862

Hay S, Obee T, Luo Z, Jiang T, Meng Y, He J, Murphy S and Suib S (2015)  The viability of photocatalysis for air purification. Molecules 20(1): 1319-56

Nazarenko Y (2020) Air filtration and SARS-CoV-2. Epidemiol Health 42

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