Can I use UV light to disinfect Totobobo filters?

Precaution!
– UV is very harmful to the eyes and can cause skin cancer.
– Conceal the UV light inside an enclosed space.
– Do not allow children or pet approach when the UV light is turned on.
– Some UV light generates ozone, which is harmful to the lungs.

Recently, we have received a couple of emails from our customers with the same question.

Can I use UV light to disinfect the Totobobo filters for reuse?
Does the UV light kill the filter’s effectiveness?

These are interesting questions that we have yet to explore. UV-C devices (tube or LED) for decontamination are not difficult to find nowadays. However, there is an obvious concern that UV exposure may degrade the plastic filter material and it may kill the static charges embedded in the filter media, reducing its’ filtration efficiency. After all, we all have seen how plastic turns brittle after long exposure under sunlight. What if the UV device turns the filter media brittle? or somehow reduces the static charges in the fabric?

We decided to do a simple test to find out how does the UV light affects the filtration efficiency of the filter media?
We use an off-the-shelf UV lightbox and conducted a simple exposure test on our filters (F94, F96, and Pro99).

The procedures of the tests as follows:

1: Perform a quantitative fit-test (TSI PortaCount Pro) and record down the result (fit factor=x) before exposing the filters under UV.
2: Expose the filters under the UV lights
3: Mount filters onto the mask
4: Conduct the quantitative fit-test again under the same condition.
5: compare the result before and after the UV exposure

How does the PortaCount machine works?
The PORTACOUNT measures the concentration of these particles around the person’s head and then measures the concentration of those particles that leak into the respirator.
The ratio of these two numbers is the “fit factor”. A fit factor of 100, for example, means that the air inside the respirator is 100 times cleaner than the air outside.

TSI PortaCount

Remember, the main concern we had was whether the UV exposure would in some way deteriorate the filter’s electrostatic charge and degrades the efficiency and mechanical property. Read more below to find out!

We started the test off with a 1-hour UV exposure, to our surprise, the fit factor remained at the top level (200+), same as before the UV exposure.
The fit-factor is determined by two parameters, (1) how well the mask fits the face, and (2) the filtration efficiency of the filter media. Since the first parameter is fixed (same person, same mask), a change of the fit-factor would indicate a change of the filtration efficiency.

We decided to push it further, to a longer time frame of 3 hours. The results remained the same, showing the filters are holding the performance at the top-level even after 3 full hours of exposure to strong UV light.

Encouraged by the results we’ve gotten for the previous 2 tests, we decided to go another step further. We let the UV rays shine upon the 3 different sets of filters for an additional 2 hours, accumulated a total of 5 hours of UV exposure, and then perform the test again. The results remain the same! These filters are as good as new after a 5-hour under very strong UV radiation.

Frankly, we were quite surprised and impressed by the performances. Initially, we thought the UV radiation would destroy the filters and degrade its filtration performance. It turns out that the filtration efficiency is not really affected by UV light exposure.

In conclusion, filter efficiency is not likely to be affected by a few hours of UV exposure. (e.g. germicidal UV-C light) Such duration is more than enough to provide 4-5 times of 15 minutes UV-C decontamination sessions.

For additional safety, we recommend changing the filters after each visit to a high-risk area (i.e. crowded hospital). Disinfect the used filter with UV-C and rest for a minimum of 3 days in a clean space before reuse.

Precaution!
– UV is very harmful to the eyes and can cause skin cancer.
– Conceal the UV light inside an enclosed space.
– Do not allow children or pet approach when the UV light is turned on.
– Some UV light generates ozone, which is harmful to the lungs.

Reference reading:
Addressing COVID-19 Face Mask Shortages [v1.1]
Evaluation of Five Decontamination Methods for FFPs
FB: Open source COVID19 medical supply

Brave and happy Austrian dentists

Healthcare workers are the unsounded hero of the ongoing war against the COVID-19 virus. Here in Totobobo, we are glad to be able to play a small part to bring happiness to this team of Austrian dentists. The story unfolded as illustrated in the following email exchange.

2020-03-30 from Dr Tünde Alföldi, Austria
Hi, we’re dentists in Hungary and Austria. We’re at high risk because we spread saliva in the air during the procedure, and we have the Covid-19 in our countries. To buy medical masks is impossible, so we look for an alternative solution to protect our team. Which filters should we buy?  Thanks

2020-03-30 from Francis (totobobo)
For the highest protection, we suggest the PRO filter, which is N99 equivalent. https://www.totobobomask.com/product/totobobo-noseclip-pro
The PRO filter unit: https://www.totobobomask.com/product/pro-filter
The PRO filter refill sheets: https://www.totobobomask.com/product/pro-filter-refill
I need to highlight the differences between the Totobobo mask, N95, and surgical mask:
There are pros and cons.

https://www.totobobomask.com/faq-coronavirus-covid-19
A published pilot study by the Prince of Wales Hospital indicates Totobobo mask is able to fit more people than the N95 mask (70% vs 40%) which is important for providing effective protection. However, when the mask is well fitted, N95 mask provides a higher level of protection than Totobobo (scoring 193 vs 133, where 100 is the passing mark).
Large size is suitable for men. Medium/small size is suitable for most women.
You can use the “Size chart” for a quick check:
If you need a more accurate size estimation, please download and print this template, to make a simple paper dummy mask. That allows you to check and compare the two sizes physically.
Let me know if you have any questions.
Best regards, Francis

2020-03-30 from Tünde Alföldi dr
Dear Francis, I`ve measured our team as you’ve sent me the form, we would need 4 big (L) TT-01 and 4 small TT-02 (S). This is not enough for all the team in Austria and Hungary, but in case we could preorder that amount would be great, and if you have more for delivery then we would like to order more. Do you mean replacing the filter after one day or after each patient? I have an Ozone machine, do you think instead of UV we can sterilize with that the filter? Thank you again and I`m so happy that you help us! Kind regards Tünde

2020-03-30 from Francis
Hi Tünde,
I’m not familiar with the Ozone machine and its effects. If it can disinfect a normal N95 mask without damage, then it should be fine.
Ideally, you need to change the filter each time coming out from the ICU. However, if the resource is extremely limited, you can use the filter for the whole day. You need to be especially careful not to move between virus-carrying patients and other patients to avoid cross-infection. 

2020-04-15 from Dr Tünde Alföldi
Dear Francis,
We just got the masks yesterday because the Austrian custom did not want to let it through because we‘re not importers. But finally after paying a high custom and having long arguments we got it!
Thank you for your help!
Let me know when it‘s possible to buy more masks and filters, please!
Kind regards
Tünde

2020-04-15 from Francis (Totobobo)
Dear Tünde,
Wow, thank you for this cool picture, you look very professional! (is there a face shield flipped up?)
Do let me know how your team thinks about the mask/filter. I’m eager to know.
Stay safe and take care,

Francis

2020-04-17 from Dr Tünde Alföldi
On the photo it‘s my husband:), and it‘s a face shield extra over the face. In case you want to advertise that you help doctors feel free to use that picture, we‘re very grateful to you! We got from the Austrian government 6 pieces of FFP3 masks for the whole surgery (we‘re 7 people), and they said you can steam-sterilize it- which actually could deform them, and they gave it only in one size, in the biggest, so it‘s mostly not fitting on the assistants’ face. In the shops they don‘t sell any FFP3s, so to get more it‘s impossible.


Everybody in our surgery says that compared with the FFPs they can breathe much better in the Totobobo mask, and you can stand it for more hours wearing it! And of course, you can fit it to your face, not like the oversize FFPs. So we are happy and we could start to work again, not leaving our patients in pain!

Dr Tünde Alföldi, Alföldi Dental System Kft., Austria


I send a picture of myself in your mask at work, your company can post it if you want, I´m grateful that I have Totobobo mask. In Hungary and in Austria they sell for dentists hand-sewed textile masks (one layer) and simple medical face masks for 10-times higher prices like usual.  I send you a picture of their offer that you see how incredible it is. In Austria they want to restart the schools in the middle of May,  I would order for my children masks-which filter you would recommend for that purpose?
Kind regards, Francis, we are really thankful for you!