Note: This is a very new project, and is evolving all the time while we bring resources online. Check out our FAQs, as they're the quickest way for us to answer things - you can follow us on twitter too.

 Do I have to have an FFP3 mask to examine patients?

We've got limited supplies of FFP3 masks? Or is it OK to use surgical masks?

At present, FFP3 masks and equivalent are in greatest demand and greatest shortage.

The UK's NHS notes that the filter grade and mask type required depends on the type of procedure you're undertaking, so in some circumstances, the less-protective Surgical or FFP1 masks are acceptable - please see their latest documents for guidance.

You can see advice about upgrading P1 (or any other) respirator cartridges to P3 with fairly readily available pads or filteration material in our youtube video here.

Note: 'FFP' stands for 'Filtering Face Piece' and is usually attached to disposable masks - an equivalent respirator grade is usually labeled simply 'P3'.

Do masks need to be CE Marked?

For masks to be used by Health Care Professionals (HCPs) and Volunteers (HCVs) they should carry the relevant quality certification markings for your country; in the case of the UK that's the CE mark.

If you are producing masks rapidly for humanitarian reasons, e.g. as a "Maker", take a look at the UK Gov't Medical Devices CE Conformity page from which I've extracted this:

Exemptions You should not place a CE mark on your medical device if it is:

  • a custom-made device – although it must still meet the requirements in the directives and the type of device should be labelled clearly
  • undergoing a clinical investigation – it must include ‘exclusively for clinical investigation’ and meet the requirements as far as possible – you must take precautions to protect the health and safety of patients
  • an in vitro diagnostic medical device (IVD) for performance evaluation
  • a non-compliant device used in exceptional circumstances (humanitarian grounds)

You don’t need get these checked by a third party to show they conform with the requirements but you need to draw up a statement to declare their compliance for custom-made devices, clinical investigations and performance evaluation devices.

We'll attempt to get clarity on whether masks produced for Health Care Professionals can be used without the CE Mark on humanitarian grounds.

Can I disinfect respirators with bleach?

Surely dipping in bleach will disinfect!

Yes, it looks like this might be a good way of disinfecting respirators! A full, peer-reviewed procedure is given here, which we've just come across thanks to Shafa Wala on the Coronavirus Tech Handbook facebook page

We've not yet rehearsed the guidance ourselves - at first glance it seems like a great solution, but we do worry about skin irritation from long term exposure to straps that have been cleaned in bleach.

What we're doing about it:

  1. As soon as we can we get time we'll boil down the steps into an easy and printable how-to.
  2. We'll review the guidance and recommend any extra steps that we can think about to keep users comfortable in the long term with day-in day-out usage.

Why not just use UV-C?

Shining concentrated UV-C light, from a cheap lamp, onto a mask would sterilise it. Why not just do this?

Absolutely right, and we've already got some UV-C lamps on order for testing. There are two main concerns here:

  1. UV-C light denatures some plastics, and especially rubbers. We don't want to recommend something where the mask itself is sterilised, then the strap breaks halfway through your exam! The valve getting brittle needs to be considered too.
  2. Filter cartridges for respirators are also made out of plastic, which not only could denature and break, but which is opake and in a complex shape - so we doubt that the penetration of light is sufficient to for complete sterilisation.

What we're doing about it:

  1. We're looking into a solution for alternative straps that are resilient to UV, and checking with mask companies if the valves are made of a UV-resilient plastic. If they are, this would be a very neat solution since UV sterilizers are available off the shelf.

  2. We might consider a disassembly procedure for filter cartridges enabling them to be safely put through a UV tank. (Also need to check how many cycles the plastic can withstand).

What's wrong with hot water? That'll kill it!

Washing masks in hot water should kill the virus, why not do that?

Most of the filter pads and masks comprise some kind of paper. They're P3 masks, meaning that the paper/cotton is tightly and specifically woven to avoid penetration of extremely fine particles like aerosols.

Although washing might be a last resort, we're concerned that the weave will be disrupted by the washing process, and then would allow finer particles through.

What we're doing about it:

  1. Nothing right now, although if we get access to a lab we might be able to run some tests so see if there's (f/ex) a number of times they can be washed without reducing in efficacy.

Can I put it in an oven?

Surely the heat from the oven will kill the bugs?

Most normal ovens don't have great temperature regulation in the range 50-80 degrees C (above which you're just gonna burn that mask!). So there's no way of being sure that the virus has been exposed to sufficient heat for sufficiently long.

Also, most ovens won't be hermetically sealed, and fans will blow the infection everywhere (you'd need to control the exhaust temparature).

Also, for those of you thinking about using domestic ovens... and this can't be overstated: Do you really want a coronovarius-infested mask in the thing you cook with?

However if you've got access to an industrial oven, and you're able to get the infected masks to it safely, and it's temperature controlled in the right range, and it's either hermetically sealed or you have ability to superheat the exhaust gases then you might be on to a winner.

What we're doing about it:

  1. They're not there yet but we're compiling an easy lookup (it will be hosted here) on the required temperatures and durations required for sterilisation. We've come across stuff on safe exhaust temperature too so will add that soon.