SCI-ART LAB

Science, Art, Litt, Science based Art & Science Communication

The truth about disinfection tunnels

The Covid 19 fear has created all sorts of chaos. People are desperately trying to do all that they can to keep safe. "Keeping  safe" has become a 'relative' act now. 

We hear news about  disinfection or sanitizing tunnels getting installed in several places   across India (2,4,5). 
Disinfectant tunnel - Pic source: The new Indian express
So we tried to dig deep to find out the facts about these disinfection tunnels. Because as the pandemic  effect gets reduced, we might have to face them or pass through them to enter all the public places. 
As you pass through them, sometimes after washing your hands, nozzles spray a disinfectant mist on you which reportedly kills most germs and viruses, including, hopefully, the COVID-19. 
 These tunnels spray a mist of sodium hypochlorite solution, a chlorine compound often used as a disinfectant or a bleaching agent, as you pass through them. Sodium hypochlorite is a component of commercial bleaches and cleaning solutions and used as a disinfectant in drinking and waste water purification systems and swimming pools. In 0.5% w/v solution, it is called Dakin's solution and used as an antiseptic to clean infected topical wounds. The spray used by most Indian tunnels, is 1 per cent solution (1).  Two sets of three nozzles in the tunnel will spray the chlorine compound as people walk inside the tunnel for about five seconds .

However, The World Health Organisation (WHO) warns that these tunnels are meant to supplement, and not replace other measures like washing hands regularly, maintaining proper hygiene, wearing a mask, and maintaining social distancing.

The concentration of Sodium Hypochlorite used for disinfecting dead bodies, plastic ware and lab ware is much higher that what would be permissible to use to spray on humans due to its side effects on humans. And this comcentration of Sodium Hypochlorite will not kill the virus. The following articles also mentions that effectiveness of Sodium Hypochlorite on outdoors is not yet proven. 

https://www.sciencemag.org/news/2020/03/does-disinfecting-surfaces-...

What is alarming is a slight variation in the concentration of sodium hypochlorite could lead to mild to extremely serious side-effects, ranging from skin and eye irritation to severe burns. WHO says that chlorine was not effective to kill the pathogen on humans. On the other hand, it was potentially more harmful due to the damage it can cause to the mucous membrane and also the skin. According to   WHO, the disinfectants will work on surfaces, but not on the human body, and can also harm people. “Spraying alcohol or chlorine all over your body will not kill viruses that have already entered your body. Spraying such substances [alcohol or chlorine] can be harmful to clothes or mucous membranes [eyes and mouth],” WHO said in its advice to the public.  

The chemical, sodium hypochlorite, had gained infamy after the outrage triggered by the Uttar Pradesh government using it to spray on migrant labourers who were returning home from Delhi. Such disinfectant tunnels were first used in China, the epicentre of the COVID-19 outbreak. However, even there, they had proven to be ineffective.
The World Health Organisation has added that sodium hypochlorite exposure may cause nasal irritation, sore throat and coughing. Exposure to stronger concentration of the chemical can cause serious damages including burning pain, redness, swelling and blisters.

As these tunnels will create a false sense of security and people may be diverted from hand wash to disinfection tunnel, and also the spraying of alcohol/chlorine/lysol on human beings is not only harmful but also ineffective, some governments were forced to discontinue (3) .

 To avoid dangerous mishaps, It is important that the government quickly formulate and enforce guidelines for these tunnels or totally ban them.

Updates: On 25 the April, 2020, TOI reported (6) that scientists who studied these tunnels in India concluded that ...  Using a scientific design and correct amount of disinfectant inside spray tunnels can actively reduce bacteria and other microbes on clothes and external body.
Not following the scientific rules and mismanagement created the problems people are facing now according to them. People are not using this scientifically, they alleged. Either they use a higher concentration of the solution (which makes it unsafe) or dilute it too much which renders it useless, they say. The study suggested that for people allergic to hypochlorite solution, benzalkonium chloride can be used.
The study said 0.02-0.05% weight concentration  did not show any adverse effect on normal skin flora  and yet destroyed the standard microbes. They recommended that using 0.02-0.05% weight concentration  sodium hypochlorite solution (200 to 500 ppm)  ) for external body surface sanitization  of personnel walking through the mist tunnel  by following standard safety precautions.
They also suggested these things:  For people with a high probability of exposure like health  workers, police and municipal employees  the solution with 0.05% weight concentration is suggested.  For those in normal office spaces, the solution  with 0.02% weight concentration is suggested.
The disinfection tunnel designed by the ICT Mumbai  recommends the concentration of the benzalkonium chloride  of 30 parts per million (ppm).  The scientists further recommended the use of face shields  or safety goggles for safety purposes during the walkthrough. 
Okay, but who is going to monitor these safety measures recommended by scientists?

Footnotes:

Views: 295

Replies to This Discussion

Permalink Reply by Dr. Krishna Kumari Challa on April 14, 2020 at 9:01am

229

https://docs.google.com/viewer?a=v&pid=forums&srcid=MTAzMTQ...

https://docs.google.com/viewer?a=v&pid=forums&srcid=MTAzMTQ...

https://docs.google.com/viewer?a=v&pid=forums&srcid=MTAzMTQ...

https://www.sciencemag.org/news/2020/03/does-disinfecting-surfaces-...

https://docs.google.com/viewer?a=v&pid=forums&srcid=MTAzMTQ...

I read the 'blurb' on science magazine and it is not very carefully written. However few things are clearly mentioned in this blog post as well:
1. Bleach at low concentrations is indeed effective in killing the Corona viruses (did not mention SARS-CoV-2 specifically).
2. Outdoor spray of very diluted bleach 'may not' be effective as the UV rays might break down the bleach.
3. The article clearly says bleach is effective in killing the virus but its not clear whether it can kill the viruses floating the air.
Please find another review article suggesting that Sodium Hypochlorite is indeed effective in killing the virus in as low as 0.21% (highlighted).
--
1.The article that you have sent has many inconsistencies. The summary says 0.05% of Sodium Hypochlorite is effective whereas nowhere in the results or the discussion do they mention this.
2. The statements that you have highlighted, the first one is from suspension test of the disinfectant. This specifies that at least 0.21% of Sodium Hypochlorite is necessary for disinfection with exposure for 1 minute so that the virus is effectively killed. In suspension tests the disinfectant is directly added to the suspension of the virus. This wont be the case for disinfection tunnels. 
3. The second highlighted statement is part of carrier tests. The statement says that the typical concentration results to 0.05% of Sodium Hypochlorite. But the very next statement says that the data in their research suggests that minimum concentration of 0.1% is effective on surfaces. Does the dilution should be 1:50 and not 1:100. In carrier tests the microorganism is applied on the surface left to dry and then disinfectant is applied on the same surface. 
4. Again at the conclusions it says that 0.1% of Sodium Hypochlorite is effective for SURFACES. And they also mention that this data is for coronaviruses that the World has seen before. They "expect" it to work in similar way with SARS-COV2 but there is no evidence that these concentrations will surely work. 
5. People that are using disinfection tunnels are suggesting to use 0.05% of Sodium Hypochlorite which would be less to spray on humans and expect to kill the virus effectively considering all other evironmental factors such as organic material and UV. And there is no gaurantee that the disinfectant will on the human body for entire one minute after spraying. And spraying for entire 1 minute would harm the human body way more. 
6. Coming to the point of this thread, Sodium Hypochlorite could do more damage than effective killing of the virus. 
The point of this thread is whether disinfection tunnels will provide effective killing of the virus, from the data so far not much is know about this new coronavirus and spraying human body with a higher concentration of Sodium Hypochlorite will cause more problems in the future.

RSS

Badge

Loading…

Get Badge

Birthdays

Birthdays Today

Birthdays Tomorrow

© 2024   Created by Dr. Krishna Kumari Challa.   Powered by

Badges  |  Report an Issue  |  Terms of Service