Disinfectant tunnels: a solution to the problem or a problem on its own?

© Author(s) (or their employer(s)) 2022. No commercial reuse. See rights and permissions. Published by BMJ. INTRODUCTION The Coronavirus disease 2019 (COVID19) pandemic has impacted the health and socioeconomic status of millions of people worldwide. COVID19– related health policies 2 introduced around the world contain methods to curb the transmission of the virus, and these include border control measures, contact tracing and lockdown. As the world enters the third year of living in the COVID19 pandemic, countries have attempted lifting movement restrictions only to face yet another wave of the virus transmission, resulting in the continuous cycle of transmission, lockdown and reopening. To break this cycle or delay the next wave, Cacciapaglia et al suggested that the key was to limit the number of persons infected during the interwave strolling period. However, aside from the commonly used approach of movement restrictions that has negative impacts on the economy and mental health, 6 another approach that could be considered would be physical devices that can prevent spread of viruses. Novel ideas on automated disinfectant devices have emerged as a means to reduce risks of viral transmission. One such device is a disinfectant booth or tunnel, which has been developed and deployed in as many as 16 countries, including Singapore, China, the middle East and Russia, in an effort to increase sanitisation and minimise transmission of the virus. 9 The type of disinfectant used in these disinfectant tunnels differs, ranging from benzalkonium chloride (BAC) to sodium hypochlorite and even Ayurvedic remedies. 10 BAC is a quaternary ammonium compound, largely used for its properties as an antiseptic and disinfectant. It has reported efficacy against coronaviruses and has been used as one of the main active ingredients in the disinfectant booths or tunnels deployed. However, such disinfectant systems are currently not recommended by WHO. The safety profile of the tunnels is not clear, especially regarding potential pulmonary side effects. In vivo studies suggest pulmonary toxicity associated with BAC. 15 BAC has also been implicated in the development of occupational asthma, as an airway irritant as well WHAT ARE THE NEW FINDINGS ⇒ This is the first pilot study to look at the bronchoconstrictive effects of aerosolised BAC. ⇒ Findings from this pilot study suggest that BAC disinfectant tunnels/booths cause bronchoconstriction even when used with a surgical face mask. With N95 respirators, no conclusive objective evidence of bronchoconstriction was made, but subjective symptoms were reported. ⇒ Hence, conclusion regarding safety cannot be made.