DIY ResMed S10 Air Inlet UVC Bug Killing System

[MoreBeers]

Hello Folks!

This is just an early idea, and it may not be viable.

In the next four weeks, I am off for major Colon Cancer surgery (they are removing my entire right side, or left side as you look at me), so will be taking my ResMed S10 along with me for use at night after the Surgery (hopefully I will still be around then to need it)!

I will be fairly comprehensively beaten up by the time I wake up so, the very last thing I want, at that stage, is to catch some respiratory infection as an added extra.

I will be cleaning my ResMed S10 fully before Hospital, with a new Hypoallergenic Inlet Filter.

I have also bought an in-line Virus/Bacteria Filter for the pipe, just to add an extra layer of protection. I have no idea how good these are but, if nothing else, it's an extra Filter between the Ward Air and my lungs.

The point of this Thread is because I was wondering if I could create a pre-Inlet UV sterilising unit using, say, UVC LEDs that work at around the 260 nm range.

Suitable ones seem to need 6-7 Volts, so I would also need to add a PSU, or I may be able to take a feed from the ResMed S10's 24 Volt PSU, and crank that down to the correct Voltage. The LEDs do not draw very much, so the ResMed PSU should cope with the extra load.

As I understand it, UVC at around 260 nm is the optimum range to disrupt the DNA of viruses and bacteria, effectively killing them or rendering them sterile in terms of infection.

I also gather than UVC at that wavelength does NOT produce Ozone, so the air passing through this, should be safe to breath. Indeed, I gather that wavelength destroys Ozone. If I understand this correctly, it is UVC below 200 nm that generates Ozone.

I was thinking of making a neat box to fit onto the Left Hand side of my ResMed S10, to snugly fit over that end, so that no UVC light can escape, or be seen.

Inside I could fit reflective mirror plastic, and perhaps 6x UVC LEDs, so that the whole void inside of the box is bathed in UVC light.

I could also fit a large Air Filter unit to one side too, just as an added measure. So all air being drawn in has to pass through an extra Filter.

The inlet air pressure is not great, so a suitable well ventilated void should be fine, even if it has a Filter.

The key is to zap the air passing through this unit with UVC, which should hopefully wack any airborne bugs and nasties as they pass though and into the Air Inlet of the ResMed.

Is this worth exploring?

Or, are there any dangers that I am not aware of?

I am no UV expert, so am happy to be educated or ridiculed!

Any thoughts on this?

MoreBeers

[Crimson Nape]

First, I want to wish you the best of luck.  I feel you are overthinking this and need to take a step back.

Inline Filters:  Be aware the inline filters severely hinder the proper pressure setting and can cause more problems than they are worth.  The CPAP's pressure sensor is at the machine.  There is an option for an antibacterial filter on the Resmed, but each filter manufacturer will have a different flow restriction rating.   There isn't any adjustment on the Resmed to account for this variance.  Plus, if you use your humidifier, the resistance will change as the filter becomes saturated with moisture.

UV Light: If the UV light is strong enough to kill bacteria, then it will have to be totally enclosed and eye protection required by anyone entering your room, as well as warning placards posted.  Have you run this by hospital officials?  I don't think they are going to be very agreeable to this.  Also, if the air in the hospital is good enough to breathe, then it is the same air that will be used by your CPAP.   Anyway, the use of UV or Ozone devices voids your CPAP's warranty. Additionally, plastic degrades in UV light.  A UV retardant is required to be added to the plastic's recipe when it is being produced to address this.  Unless you purchase UV resistant plastic, you are asking for a bad time.

- Red

[MoreBeers]

Hello Red!

>> First, I want to wish you the best of luck. <<

Thanks, it's a big one, so big risks, but the Surgical team are switched on.

Firstly, I need to clarify that this is probably only for 5-7 Days whilst I am in Hospital. After that it will not be used so, it's not for long-term use. The idea is just to buy me a little extra protection to avoid going down with something else nasty, i.e. whilst I am trying to recover from something already nasty (AKA the Surgery).

>>  I feel you are overthinking this and need to take a step back. <<

Fully understood, the sad fact and genuine risk, is that UK Hospitals are effectively where you often go to get more sick, many go in with one thing, and come out with a parcel of other things!

I am no hypochondriac, so this idea is purely pragmatic to try and lessen the odds of picking up a respiratory infection when out of Theatre, and for the time when CPAP will be needed when going from Recovery, then to a Ward.

Also, this is just for night-time protection when using the CPAP. My thinking being that it might buy me an extra safety margin for maybe 40% of the time in there (i.e. at night on CPAP, or if sleeping during the day and also on CPAP).

I'm just trying to reduce the scope for catching anything whilst breathing air via the CPAP, if I can make that slightly safer than when, say, breathing normally during the day without CPAP.

I am thinking here of airborne bacteria and viruses.

Even with just the ResMed S10, with the CPAP it's arguable that I already get a little extra protection due to the machine's inlet Filter (I use the Hypoallergenic Filters which are good at keeping out dust and crud if nothing else), so anything has to get past that.

However, I am aware how small virus particles are, so it may be arguably moot, like trying to stop mosquitoes with Chicken Wire!

That was why I pondered the idea of improving things by zapping the air going into the machine with UVC first.

>>Inline Filters:  Be aware the inline filters severely hinder the proper pressure setting and can cause more problems than they are worth.  The CPAP's pressure sensor is at the machine.  There is an option for an antibacterial filter on the Resmed, but each filter manufacturer will have a different flow restriction rating.   There isn't any adjustment on the Resmed to account for this variance.  Plus, if you use your humidifier, the resistance will change as the filter becomes saturated with moisture. <<

Yes, thanks, I had some idea, and had read that fitting the in-line Filter at the Mask end can reduce the scope for the machine to get confused by the resistance changes.

One possible advantage, is that I already run my S10 in CPAP Mode at the maximum 20 cm H2O, so it's already effectively a constant thrust variable noise machine!

That may help to a degree, because I am asking less of the S10 than, say, those on variable Pressure settings.

I noted the option to specify use of an in-line Filter, so I did wonder if that simply adds a little extra Pressure? I have a manometer, so I may try to see if this does provide extra puff, even without the Filter in place for example.

I will update if I spot any Pressure advantages to specifying a Filter (even without one fitted for example).

>>UV Light: If the UV light is strong enough to kill bacteria, then it will have to be totally enclosed and eye protection required by anyone entering your room, as well as warning placards posted. <<

Just to clarify, it won't be a huge great thing, I am thinking a closed box glued to the side of the S10 (I have spare side panels, so can sacrifice one for just this purpose).

So, the plan would be that the UVC light will not be visible from any angle. It would just be an extra unit on the left of the machine, glued on solid. As I say, this is only for a one time use, so I won't need easy access to change the Inlet Filter. I could use screws or bolts, so it has to be disassembled with tools to get inside that area.

>> Have you run this by hospital officials? <<

That's quite a challenge at the best of times!

>> I don't think they are going to be very agreeable to this. <<

Probably not, but if the unit is totally sealed such that no UVC light can be seen, then I'm not about to tell them!

>> Also, if the air in the hospital is good enough to breathe, then it is the same air that will be used by your CPAP. <<

Yes, the same air, but if this idea is workable, then by the time I get to breath it at night when on CPAP, it should have gone past an outer new Inlet Filter, then been zapped with UVC, then gone past the S10 Inlet Filter, then an in-line Filter, then into my lungs.

Same air, but hopefully more sterilised and also filtered.

>> Anyway, the use of UV or Ozone devices voids your CPAP's warranty. <<

Not a problem, it's an NHS Unit, and I have a couple of spares, so in my case that isn't an issue, but I agree it could be for others.

>> Additionally, plastic degrades in UV light.  A UV retardant is required to be added to the plastic's recipe when it is being produced to address this.  Unless you purchase UV resistant plastic, you are asking for a bad time. <<

Noted and understood, but this is only for a maximum of 10 Days use, so the question then is can the UVC cause any issues with the plastic in that short time, that may affect the safety of the air that I breath?

I am absolutely not into wearing face nappies, but did note that there are now some fancy ones available that incorporate UVC into a powered Face Mask. So that would be something about the size of a Wood Working Mask. The device I am thinking of making only needs to be about the same size, albeit it will be rectangular and firmly attached to the side of my S10.

What is driving me, is the unfortunately high chance that I will pick something up whilst in Hospital, right when I really could do without that extra hassle. If I can lessen those odds, then it is worth trying so long as this idea does not introduce any new risks.

Rest assured, I won't be running with this unless it is 100% safe both in terms of me breathing it, and anyone else being affected by the UVC light (which should be totally encased so as not to risk that). I can certainly add Warning Stickers, but it will still be me operating the CPAP.

I could, for example, wire it so that it only operates when the CPAP is blowing, to further reduce any scope for anyone to see any UVC light.

Thanks again for your input, I hope you can see where I am trying to go with this?

MoreBeers

[MoreBeers]

Hello Folks!

To try and visualise what I have in mind, imagine a Toilet Roll Tube, lined inside with Mirror Plastic, and with 4x UVC LEDs inserted around the inside of it, possibly in two rings of 4x UVC LEDs.

Then an Inlet Filter at one end, then a cover outside of that, so no UVC light is visible at the inlet end.

The other end is blanked off, apart from an Aperture in the side of the tube the same size as the existing S10 Inlet Filter, into which the air flows after being zapped with UVC as it flowed through this new unit, before entering the S10.

So any virus or bacteria flowing in along with the air, will get significant DNA damage on the trip through, rendering them ineffective.

With the mirrored inner surface, and rings of UVC LEDs, the UVC light will be all around the inside of the tube, so there is nowhere for the virus or bacteria to hide.

It does not need to be a tube, but a tube has the advantages of no corners to hide in, and no shaded areas.

This tube could be enclosed inside of a Box shape, so that it is just an unobtrusive oblong module firmly attached to the left hand side of the S10.

In terms of the UVC LED operation, I could patch in a small Relay that is linked to the S10's upper CPAP on/off switch, so that the UVC LEDs only illuminate inside when the CPAP is blowing. Indeed, I may be able to just patch into the CPAP On/Off Switch, as the UVC LEDs are only 6-7 Watts.

I hope that helps to envisage what I am considering.

At the moment I am mainly wanting to know anything that suggests this is not safe in terms of breathing the air that has flowed through it.

Please assume that no UVC light will be visible from outside of this proposed unit.

MoreBeers

[Crimson Nape]

OK! Let's say your bug zapper does achieve your desired results. That basically takes care of 8-12 hours. What do you plan to breathe the other 12 to 16 hours?

- Red

[MoreBeers]

Hello Red!

>> OK! Let's say your bug zapper does achieve your desired results. That basically takes care of 8-12 hours. What do you plan to breathe the other 12 to 16 hours? <<

Well, look at it another way, this would reduce the daily risk by 40-50%! Those are already good odds.

But, when awake and not using CPAP, there are other methods, such as an hourly squirt up the bugle holes with a saline nasal spray! Salt is a hostile environment for bugs.

Plus a quick gargle every visit to the bog, using a quality mouth wash. In tests they found this is effective, and can kill 99% of bugs in the mouth and upper throat area.

Iodine based mouthwashes came out top, right alongside Listerine.

Indeed, cheap Hydrogen Peroxide (H2O2) will kill over 90% of bugs, even when used at 1.5%.

Or water and salt.

In fact, even gargling with just plain water, came out better at killing bugs in the mouth and throat than doing nothing!

Or a quick nebulisation with Saline, or Saline and Hydrogen Peroxide mix (many Doctors carry small hand held units, and use these when ever they suspect any exposure to something nasty)!

We have a neat small Nebulising unit that can be either USB powered or powered via 2x AA Batteries, that accepts a small Vial of Saline Solution plus any H2O2 we add. Really neat, and clears the airways and lungs. I could easily pack that along with a pile of AA Batteries and Saline Vials, and that would take up no space at all, so could be part of my wash bag.

All of the above can be done easily and unobtrusively during the day, and would reduce the risk of picking up a respiratory infection by a significant factor.

This is quite a serious issue, because so many do pick up new respiratory bugs when in Hospital. It's not a major issue if you are just going in for an X-Ray, but it can spoil your whole day if going in to have half of your guts removed! Last thing one needs then is some avoidable infection tipping a potentially delicate survival balance the wrong way.

The measures I am proposing are thus automated when using CPAP, and easy to do when awake when not using CPAP.

Between the two, I think I can safely reduce the potential risk significantly, and without bothering anyone, or needing any help to manage it.

Indeed, nobody would need to know.

I hope you can see what I am seeking to achieve.

MoreBeers

[Jeff8356]

MoreBeers,
I have to say I admire your tenacity for coming up with these different ways to keep yourself germ free!
My immune system is below par (auto-immune disease and medications) and I fear hospitals for many the same reasons you listed.  I have been putting off knee surgery for the last 2.5 years because of it.  I have seen what they do to sanitize in some hospitals, or more precisely how poorly they do it.  Not a very comforting thought for me.

But I have to admit I agree with Red!  Unless you are in some hermetically sealed pressurized room you will be breathing in all the same air throughout the hospital.  Wearing an N100 mask may help during transport but isn't practical.
There doesn't seem to be a perfect answer for this other than hoping the ward you will be in has an infection control team that cares and does a great job to keep patients from getting sick.

Any chance you could go without CPAP for just that one night?  Just use O2?  I recently had somewhat complicated oral surgery and couldn't use my APAP for two weeks by the surgeons orders.  It turned out to not be as bad as I thought.  But of course I wasn't fighting micron sized germs in a hospital either.

All I can say is, I wish you the best of luck for your procedure and recovery.....

[MoreBeers]

Hello Jeff8356!

>> I have to say I admire your tenacity for coming up with these different ways to keep yourself germ free!<<

Apologies for this fuss. It's not something I am overly fixated upon, a lot of the above practical measures we already do routinely, such as good oral hygiene before using CPAP, which covers mouthwash and saline nasal spray just to start every night off well.

If visiting Hospital then, when we return home, we have just got into the habit of doing a quick nebulise and gargle, to whack anything on the head that has been picked up when there. Takes no time at all, and just seems to have helped us to avoid coming home with something extra!

We've never complied with the face mask tyranny thing, so the above are just sensible precautions that I urge everyone to consider doing, to neuter bugs that will inevitably get picked up in high density and higher risk areas, such as Hospitals where the unwell inevitably congregate!

>>My immune system is below par (auto-immune disease and medications) and I fear hospitals for many the same reasons you listed.  I have been putting off knee surgery for the last 2.5 years because of it.  I have seen what they do to sanitize in some hospitals, or more precisely how poorly they do it.  Not a very comforting thought for me.<<

Sorry to hear that. I certainly do know the knee feeling, I need a complete new left one (bone on bone, always partially dislocated, with only one competent ligament left), a right hip and an ankle or two, but all surgery plans went sideways during the recent panic. I've given up on that surgery, for now, and am just cracking on with those problems, as best I can, because I do not have a great deal of faith in the medical profession. I would not be having the Colon surgery unless I had to, and it looks like I have to!

>>But I have to admit I agree with Red!  Unless you are in some hermetically sealed pressurized room you will be breathing in all the same air throughout the hospital.  Wearing an N100 mask may help during transport but isn't practical. There doesn't seem to be a perfect answer for this other than hoping the ward you will be in has an infection control team that cares and does a great job to keep patients from getting sick. <<

I do fully understand this, my aim is just to reduce the odds, rather than not trying, and then later wishing I had tried something, but didn't.

>>Any chance you could go without CPAP for just that one night?  Just use O2?<<

Possibly, my Oxygen should be monitored closely for the first night, the main snag is my Sleep Apnoea is worst when on my back, so I try to sleep on my right side. Unfortunately, I will inevitably end up on my back after the Surgery, and won't be allowed on my side again for a couple of weeks at least (due to the internal re-connections and main surgical wound).

So, basically, on my back is the very worst position for Sleep Apnoea, and compounded if flat on my back which I avoid like the plague (I used a foam wedge under my pillows which keeps me at an angle, usually!). Even with my S10 running in CPAP Mode at the full 20 cm H2O, if on my back, I can get a dense series of Obstructives and high AHI, until I go back onto my side.

Usually, because of my severe Osteoarthritis in all lower joints, I am most comfortable on my back, but on my side is best for Sleep Apnoea, and can be comfortable, until the hip and knee pain kicks off, then I involuntarily end up on my back to relieve the - often severe - joint pain.

I just know I will wake up after Surgery, flat on my back, and with Sleep Apnoea suffocation thrown in on top of the abdominal issues! Then I will be hard pressed to deal with it myself, without risking some injury to my re-connected digestive pipework!

Another factor is that the Surgery already requires that patients must engage in deep breathing ASAP after coming round, to vent the lungs fully after 3-5 hours of Anaesthesia, to avoid a respiratory complication.

This gets complex fast, because another complication from major Colon surgery, is the digestive system shutting down, linked to the paralysing effect of the opiates upon the small intestine, that they must use during and immediately after Surgery (such as Morphine). It is a big problem in some cases, and I already try to avoid taking my opiate based pain killers because of observed cardiac effects and also mild digestive paralysis when ever I take them (I usually only need them every 10-14 days at most, because I do try to avoid them if possible). Other pain killers just do not seem to work to alleviate the pain.

I have chatted to the Anaesthetist about this, and offered to try and take as little pain relief after surgery, if that might help. I do have a high pain threshold (had 17+ operations for broken limbs in the past, so am talking from experience not optimism!). But he impressed upon me that there is a pressing need to balance pain relief after surgery, with the need to vent the lungs ASAP, which would be very hard to do without significant pain relief.

If you see what I am getting at, the objective of the UVC idea, was just to try and improve the infection risk odds if I end up on CPAP immediately after surgery, and for the first night.

If they put me on my back, which I know they must, then Obstructive Sleep Apnoea will be a significant factor, made worse the flatter on my back that I end up. I may not have any say in the use of CPAP, as they will have my kit in Theatre and, in the event of surgical complications such that I do not wake up when expected, then they will be fitting it to me if they think it is needed.

You may see why I have been pondering if I can add any extra protection to help to reduce infection risks at that critical time.

It may help to know that my surgery was cancelled a couple of weeks ago, literally as I was about to go down to Theatre, apparently because someone tested for you-know-what either in Theatre, or on the Ward afterwards. That didn't surprise me, as the pre-Admission seems to turn on a simple and unreliable spit test, so the scope for bugs to enter this chain is pretty well wide open.

>> I recently had somewhat complicated oral surgery and couldn't use my APAP for two weeks by the surgeons orders.  It turned out to not be as bad as I thought.  But of course I wasn't fighting micron sized germs in a hospital either. <<

Micron size is indeed the problem but, if you see what I am driving at, that is precisely the attraction of a UVC measure, because anything airborne has nowhere to hide if passing through an area bathed in 360 UVC 260 nm light (especially if I use mirrored plastic and multiple UVC LEDs fitted in a circular pattern x2 circles). The UVC then has the scope to disrupt the DNA of anything small and nasty as it passes through on its way to the S10 air inlet.

At home and at night when on CPAP, I also wear a Viatom CheckMe O2 for both Oximetry and for the safety buzzer, so that unit buzzes if my Oxygen levels go below the 90% threshold that I have set.

It doesn't always wake me these days!

Between the Viatom, good pre-sleep Oral and Nasal Hygiene and the CPAP, I do keep things very well controlled.

But, in Hospital after surgery, I know a few issues may then come together that could make the first 24 hours complicated, and possibly critical. I can't ask them to fit the Viatom, as that is fiddly, and the nurse tasked with doing that probably won't know how it works. So I am not planning on wearing that when in Hospital.

All I am trying to do is lessen the respiratory infection risk, if at all possible, such as when on CPAP after surgery and through the first night or two, and before I am hopefully awake enough to manage that myself. In theory, I should be woken in Theatre, and then awake in Recovery, and awake by the time I get to the Ward, so I may only then need to worry about the CPAP for the first night, but should be able to fit that to myself when needed, and thereafter manage that as usual when I am fully back in control of it.

The Hospital beds are electrically operated, so I should be able to sit myself up via that, especially if struggling to manage existing bone pain with positional Sleep Apnoea effects, and especially given that I will no longer have my usual option to roll onto my side for maybe two weeks.

One advantage that may be significant, is that I will initially be on very strong pain killers, which may help to negate the bone pain that I usually have. Indeed, that could make things work, whereas without that pain relief, it would be much harder to keep my wings level and my little bubble in the middle!

>>All I can say is, I wish you the best of luck for your procedure and recovery..... <<

Many thanks for that.

All being well, it will go according to plan, and I will be up and out ASAP. The usual is 5-7 Days in Hospital, but people can get out faster if they can get themselves mobile fast, and provided everything is functioning again. Then, they are quite happy to let people recover at home.

But there is scope for complications, ranging from death during surgery, to post-surgical internal infection, blood clots, digestion not waking up again, and the new plumbing leaking inside. Some of those can mean two months or more in Hospital, and can impact when at home and require re-admission, then a few months back in Hospital!

Can't wait!

Anyway, I will get get up as soon as I am allowed to do so. I usually bounce back faster than most, so it's mainly the initial 12-24 hours after surgery that will be the main issue, and that is when the scope for picking up a new respiratory infection is the most complex.

Rest assured, I am not some crazy person, I just want to get in, and get out, with the least trouble to the Hospital and staff. All of the above measures are self-help, and I think can be done very effectively, and without making any fuss.

The biggest fuss is to the kind people here, listening to my crazier than usual nut-job plans to zap tiny bugs with UVC!

MoreBeers

[snorin2]

Beers: good ideas; go for it! I look forward to hearing how you make your setup. What kind of bulbs ; sockets etc. Where did you get them, box, mirror etc all the details!

I believe I read or heard that there was a problem that the air molecules were not in the beam of UVC long enough in the industrial style UVC ceiling mounted units because the enclosed fan blew the air through too quickly. So would you make the box big so that the air is in there for a goodly length of time?

a little off topic but would you make sure that any drugs you are given would not preclude the use of paxlovid. you could report that as I am sure the info would be useful to others. If there was a problem, it would bolster your right to have all this equipment by your bedside!

i think it is all about the extent of the dose (of virus). I have never used the N100 masks but it appears you can buy a 20 pack. I wonder how easy it is to breathe through them? Would they not be a good idea for the awake time?

[MoreBeers]

Hello snorin2!

>> Beers: good ideas; go for it! I look forward to hearing how you make your setup. What kind of bulbs ; sockets etc. Where did you get them, box, mirror etc all the details! <<

Will do. This is very much an experiment, so please bear with me. If it looks safe and viable, I will use it.

The problem with a lot of the UVC kit sold, is a lot of it is fraudulent. They just add purple LEDs and many units emit no UVC at all! You can get Indicator Cards for around GBP 25.00 (so around USD 25.00!), which change if there is any UV Light, and also indicate if there is any UVC Light. I will get one to test that the LEDs actually emit UVC.

You may already know that UVC is invisible, so the addition of a purple LED is sensible just to warn when the main LED is active.

>> I believe I read or heard that there was a problem that the air molecules were not in the beam of UVC long enough in the industrial style UVC ceiling mounted units because the enclosed fan blew the air through too quickly. So would you make the box big so that the air is in there for a goodly length of time? <<

That was a factor I have been thinking about, the main aim is to make it as compact as possible, and basically to funnel air into the ResMed S10's air inlet so that it has to pass the UVC 260 nm light to get there, so no sneaky gaps allowing air to get in via the base area, for example.

The S10 just draws air from the room, so provided my contraption does not restrict that, or increase the inlet air pressure, then the flow from a larger space into the small inlet should not be particularly fast flowing in terms of the general mass moving towards that inlet. Sure, it will speed up as it gets sucked in, but the main mass will have a much larger relative air volume, so should move through the UVC area at a fairly sedate pace.

Indeed, the movement can probably be calculated if I can establish the flow rate through the S10, relative to the motor size and inlet pipe size. That may determine the optimum size of the UVC area that is needed to ensure a slow enough transit to stand a good chance of disrupting the DNA of any bacteria or viruses.

>>a little off topic but would you make sure that any drugs you are given would not preclude the use of paxlovid. you could report that as I am sure the info would be useful to others. If there was a problem, it would bolster your right to have all this equipment by your bedside! <<

I don't wish to be drawn on the current medication issues, all I can say is I am against most of what has been going on, I am not jabbed, and would never agree to any of the recent experimental products. I fully understand that others are happy with these issues so, with the utmost respect, each to their own.

>> i think it is all about the extent of the dose (of virus). I have never used the N100 masks but it appears you can buy a 20 pack. I wonder how easy it is to breathe through them? Would they not be a good idea for the awake time? <<

Many thanks, but I'm not one for wearing a mask. I'm happy with the precautions I have outlined above, and don't want to add the problems that a mask can potentially introduce. There is data both for, and against the use of masks, but I am sufficiently convinced by the data against that I have no faith in masks and would never wear one.

The viral load is a key issue, so I'd be pretty unlucky to receive a lung full, the most likely is that there will be stray particles in the air, and it is those that I want to zap or neutralise, if I can. Or at least increase my odds.

The whole point is I am about to undergo a very major operation, and that will be a tough challenge all by itself. I am simply trying to see if I can take out as much of the risk as possible of picking up something extra along for the ride!

MoreBeers