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.
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?