Antiviral fog could get concerts and theatres going again?

[jason5d]

Has anyone heard about "theaters could be disinfecting everyone with an antiviral "fog" that lasts 30 days."

 

I have seen them used in streets abroad this could be a way back to gigs and concerts.

 

Any thoughts??

[ImagineerTom]

There's some people playing with it - it's largely ""theatre"" though as (like contact based cleaning) it only kills virus's on the surface so however much you fog a venue or humans one infected person walking in to the room and coughing all over their neighbor will still pass it on just as much as if you hadn't fogged. Edited June 20, 2020 by ImagineerTom

[timsabre]

It sounds very similar to all those news pictures of streets being sprayed with disinfectant. Apart from the appearance of "doing something", I can't see how it would make any difference. I suppose if it makes people happier to attend the show, then it's worth doing? Edited June 20, 2020 by timsabre

[gyro_gearloose]

A quick google suggests that far-UV light might be quite effective in killing airborne bacteria and viruses. Apparently it’s quite harmless to people because far-UV cannot penetrate human skin or eyes.

[Gerry]

A quick google suggests that far-UV light might be quite effective in killing airborne bacteria and viruses. Apparently it’s quite harmless to people because far-UV cannot penetrate human skin or eyes.

Have a look at Big Clive's video:-

Cheers

Gerry

[Jivemaster]

Far UV and Ozone will kill the virus BUT both, in excess, cause human disease of their own UVC can increase the risk of skin cancer and excess concentration of Ozone leads to lung damage. Both are ideal virucides in the open but in a closed and populated space like a concert hall or theatre wouldn't fill me with confidence, Intense sunlight (with included UV) is proven to kill hanta virus in the open in southwest USA, also Ozone (generated in a portable machine) is used to reduce the smell of smoke fumes in hotel rooms between uses.

 

Just consider that a resting person breathes (in and out) about one cubic foot of air per minute, so an infected person exhaling 90 cubic feet into a theatre (or several people) during a show could infect all of the rest of the audience and perhaps the cast and possible orchestra.

Moving enough air through, to dilute any virus cloud will be hard because that's usually not what the air handling system is all about.

[adam2]

UVA light is effective against the virus, but the light is DANGEROUS to skin and eyes. The lamps that emit this light look like fluorescent tubes, but completly clear without any phosphor coating. Generally known as "germicidal" lamps. They are widely used to sterilise water, for drinking, or to control Legionela in cooling towers, or to improve the health of fish in aquiria. The lamps are inexpensive and available from all good lamp suppliers.

 

Despite the danger to skin and eyes, germicidal lamps may be safely applied in at least two ways.

 

Firstly germicidal lamps may be installed in air handling equipment to disinfect the air as it passes through into the auditorium. Care must be taken that persons servicing the equipment or replacing the air filters cant be dangerously exposed. A very small spyhole is often considered to be acceptable, for simple visual confirmation that the lamps are lit.

 

Alternatively, germicidal lamps may be installed to light an auditorium or other space when empty. Careful design is required to ensure that the lamps cant be lit with anyone in the area, and will be automatically extinguished if anyone enters unexpectedly.

 

Both the above are accepted technologies in food and pharmaceutical factories. Years ago I installed numerous germicidal lamps in a hospital laundry, not to treat the actual laundry but to sterilise laundry hampers and trolleys.

 

O/T trivia, years ago BR used ultraviolet light to sterilise the water supply in buffet cars and restuarants on trains. The water tanks were filled from a drinking water supply, but extra treatment at the point of use was considered prudent.

Edited June 20, 2020 by adam2

[Simon Lewis]

UVC (200 to 280 nm) is the most effective range for germicidal purposes - B and A have lesser effect, and the LEDs masquerading as UVC sources (as opposed to the expensive ones that can actually produce that wavelength) are criminal. As mentioned, Big Clive does a good take down of those.

 

There was some research done on far UVC (207–222 nm) suggesting that it wasn't harmful to human skin but still had germicidal properties. I might not want to be the guinea pig in that trial, though.

 

There are some caveats in using UV though...

a) ensuring that with all of the difference sources claiming effective operation that it is actually a workable germicidal light source. The beauty of using the low pressure mercury UV lamp is that the mercury spectral line is at 253.7 nm and you know what you are getting!!

b) that all the affected surfaces have been irradiated. It is easy to have shadow zones which leave viruses unaffected. Unlike (say) a properly used autoclave, it can be hard to guarantee that all parts of a room have been sterilised from virus using UV.

 

UV certainly has its place but the skin and eye exposure issues and the points above need to be considered...

[Brian]

...disinfecting everyone with an antiviral "fog"...

 

So is the idea that people walk through some sort of tunnel which is filled with this anti-viral fog?

[Jivemaster]

Disinfecting the outside of someone is only part of the solution. It's the 60 cubic feet of air exhaled by every infected person that will pass the virus to other people.

 

Every sanitiser I've seen in the hospital says "do not inhale" on the label. Every sanitiser smells strongly -not something to attract the perfume or aftershave wearers.

[djw1981]

Which is fine until one of the asymptomatic punters then coughs once inside the 'sterile' auditorium.....

[bigclive]

The current thing is the 222nm narrow band UVC wavelength that is considered too short to penetrate the outer layer of skin or even the tear film on your eyes.

 

It currently has to be generated by a specialist style of lamp called an excimer lamp that is driven capacitively. The main manufacturers are Ushio.

 

At the moment it's being used in medical environments and is basically being tested on hospital staff right now!

 

With regards to the fogging. Research into air sterilisation was done a long time ago, where the air in wards was hazed lightly with glycol just like a fog machine hazes the air. It was claimed that it had a dramatic effect in reducing cross infection by presumably having a moisture-hungry curtain of sticky droplets in the air.

Unfortunately, without modern testing on coronavirus it could be claimed to achieve those results.

 

The nightclub industry has been testing long term public exposure to airborne glycol for several decades though, with no obvious health effects.

[musht]

Possibly a dose of marketing puff in it, but interesting

 

https://www.ledsmagazine.com/lighting-health-wellbeing/article/14178406/osram-like-signify-is-ramping-up-conventional-uvc-lamps-to-fight-covid

[bigclive]

It's reassuring to know that the old fashioned mercury vapour UVC tubes are still king for high output and long life germicidal use.

 

The UVC tubes are basically a fluorescent tube with no phosphor and a uviol/quartz glass that passes UVC wavelengths.

You can buy them off the shelf at aquarium suppliers, noting that they will cause skin damage and arc-eye to humans and animals if they are exposed.

 

I'm not sure about the use of PIR switches to turn these lights off when movement is detected. They could fail and people would be exposed to the running lamp, and if you went into a room with one of the lights and fell asleep it would reactivate.

 

 

This pandemic has done three major things in UV technology:-

Created a new market for existing fluorescent technology.

Given the UVC LEDs a much needed bump. (they still fall well short of mercury tubes)

Pretty much launched the market for Ushio's 222nm excimer lamps. (A human-safe UVC wavelength.)

 

It's also resulted in lots of ordinary people having dangerous high power UVC lamps in their homes that will eventually be found by people who don't know what they are, and will suffer eye and skin damage.

 

The market for "ice blue" and near-UV LEDs has also benefited from all the fake germicidal lamps being widely sold on eBay and amazon.

[adam2]

If germicidal lamps are to be used to disinfect an auditorium, then fool proof systems are needed to prevent exposure.

 

One way would be a combination of PIR presence detectors and intruder alarm contacts on the doors, but wired such any triggering of these devices causes the lamps to "latch off" and require a key or code to reset. No question of the lamps coming on again if someone goes to sleep.

 

As a THIRD line of defence, use a time switch to only energise the lamps only when the premises should be empty.