- Spraying on streets found to be ineffective and harmful
- Spraying individuals with disinfectants not recommended
By Easwaran Rutnam
A report by the World Health Organisation (WHO) has contradicted a practice followed by Sri Lankan authorities when using disinfectants in the fight against the coronavirus.
In its Situation Report number 115, the WHO notes that the virus that causes Covid-19 is transmitted mainly through close contact and respiratory droplets, with possible airborne transmission in settings where procedures that can generate aerosol are performed.
In the report WHO says spraying or fumigation of outdoor spaces (such as streets, sidewalks, walkways or marketplaces), is not recommended to remove or inactivate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the strain of coronavirus that causes coronavirus disease 2019 (COVID-19). Streets and sidewalks are not considered as routes of infection for COVID-19.
Moreover, disinfectants are inactivated by dirt and debris, and it is not feasible to manually clean and remove all organic matter from such spaces. Even in the absence of organic matter, chemical spraying is unlikely to adequately cover all surfaces for the duration of the required contact time to inactivate pathogens.
Daily Mirror had recently reported on concerns raised by Public Health Inspectors (PHI) and Microbiologists on spraying disinfectants on the streets in Colombo and other areas.
Attempts were made to contact the Director-General of Health Services Dr. Anil Jasinghe for a comment, but he could not be reached.
The WHO report says spraying individuals with disinfectants (such as in a tunnel, cabinet, or chamber) is also not recommended under any circumstances. This practice could be physically and psychologically harmful and would not reduce an infected person’s ability to spread the virus through droplets or contact. The toxic effect of spraying with chemicals such as chlorine on individuals can lead to eye and skin irritation, bronchospasm due to inhalation, and potentially gastrointestinal effects such as nausea and vomiting.
WHO says in indoor spaces, routine application of disinfectants to environmental surfaces via spraying or fogging (also known as fumigation or misting) is not recommended.
Spraying environmental surfaces in both healthcare and non-healthcare settings (e.g. patient households) with disinfectants will not be effective and may pose harm to individuals.
If disinfectants are to be applied, manual surface cleaning with detergent and water using applied friction (e.g. brushing, scrubbing) must be performed first to ensure physical removal of organic materials, followed by the use of a cloth or wipe which is soaked in the disinfectant.
Among the most common disinfectants used which have been demonstrated to be effective against SARS-CoV-2 are: ethanol 70-90%; chlorine-based products (e.g., hypochlorite) at 0.1% (1000 ppm) for general environmental disinfection or 0.5% (5000 ppm) for blood and body fluids large spills; or hydrogen peroxide >0.5%.5- 6.
The minimal time recommended of exposition to the surface for these disinfectants is one minute or according to the manufacturer instructions.
In all settings, including settings where resource limitations may not permit cleaning and disinfection to be performed regularly, frequent hand washing and avoiding touching of the face should be considered the primary prevention approach to mitigate the suspected mode of transmission associated with surface contamination.
- Chemical spraying is unlikely to adequately cover all surfaces for the duration of the required contact time to inactivate pathogens