EH21 6RU
Edinburgh, Scotland
+44 131 618 6999

True Anti-Viral Filter in RD40

  • British technology developed in response to the 2002/2003 SARs outbreak, specifically for protection against coronaviruses
  • Standard RD40 thread for use with particular masks and NATO gas masks
  • Four layer filtration: FFP3 plus three layer electrostatic macroporous molecular sieve
  • Molecular sieve pores traps virions
  • Nano-Ag coating 3nm on sieve destroys the virions entraped in the molecular pores
  • Clear indication of when electrostatic system is operating, by blue LED
  • Powered by AAA cell
  • Designed, built & tested in the UK


The technology was developed over a 7 year period following the 2002/3 SARS outbreak, specifically to filter virus particles (virions) in the range 60nm to 180nm without the increase in work of breathing associated with conventional ultra-fine filtration.  Designed and engineering in Scotland, the technology then lay idle until the 2019 SARS-COV-2 pandemic, and is now being retooled for manufacture in the UK.

The RD40-AVM filter comprises four layers to provide FFP3 (N99) for PM2.5, with 99.995% efficiency for particulate and virions in the range 60nm to 180nm in a 38mm thick RD40 shell.  The filter layers comprise:

  1. FFP3 certified filtration outer layer.
  2. Nano-Ag coated FFP3 electrostatic pre-charge layer, which charges particulate to 30 million volts per meter by bringing them within a micron of a 30V +ve source, safe for handling and use. The 30V source is powered by an AAA cell and voltage generator within the filter.  Battery is user removable.
  3. Insulating filter layer, large pores to avoid clogging
  4. A 7mm thick Nano-Ag coated molecular sieve at -ve potential. The positively charged virions are attracted onto the surface of the negatively charged sieve, for them to be trapped in the molecular cages which are up to 230nm in diameter. A 3nm thick finely dispersed silver coating (Nano-Ag) on the sieve causes the virion to be destroyed after a period of contact.

Ordering Information


RD40 module, sealed.  Shelf life 7 years when unopened.


Patents pending.


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