DH Deciphers | Aerial spraying of disinfectants: Does it work? Is it safe?

Karnataka has announced plans to spray disinfectants on urban settings by specially designed airplanes as part of sanitation efforts to contain the aerial transmission of the novel coronavirus.

The project was to be launched as a pilot in Bengaluru on Monday but has been put on hold after experts raised concerns over the disinfectants used and their effects on people.

So what exactly is this project, and aside from the probable impact on humans, will the disinfectants really work against the virus?

What is the aerial spraying project?

The project is about spraying organic disinfectants from a height of 1,000 feet to control the spread of SARS-CoV-2 through air. A private company, Aerialworks Aero LLP, demonstrated the spraying operation with a two-seater aircraft at the city’s Jakkur aerodrome on May 29.

Read more: BBMP suspends aerial spraying of disinfectants in Bengaluru

The initial plan was to spray the disinfectants over Shivajinagar and KR Market areas for three days starting Monday, and if feasible, extend it to other areas.

Which disinfectants will be used? Will they work against the virus?

PerSapien Super Iodised water and ‘Sugaradhana Organic Antimicrobial Concentrate', a non-alcoholic surface sanitiser, are the liquids proposed to be sprayed. The solution is first compressed to very small aerosols and released in the air. Being extremely small, the aerosols remain in air for a long duration, blending with microbes, dust particles, pollen and the virus before settling down to the ground. This, says the company, can limit the spread of Covid-19 by air.

But are these disinfectants safe for humans?

Experts say the technology should not be used on human settlements without proper field testing in unmanned areas, risk assessment and public consultation. Results from field trials should be scientifically assessed in laboratories. Aerial spraying should be considered only after a detailed analysis proves that the disinfectants cause no harm to humans, animals and plants on contact.

Public health analysts feel aerial spraying from altitudes of 1,000 feet and above cannot be compared to drones that are used to spray in confined spaces at much lower heights. Drones are used to reduce human contact. But when aircraft are used over a large area, any side effect could impact a huge number of people.

Besides, any exercise of this nature covering a vast, densely populated area mandates public consent. If that is not possible individually, public representatives of that area should be consulted. The process and the impact of the exercise should be properly communicated to all so that apprehensions are addressed.

What does the company say about these concerns?

PerSapien Super Iodised water, the company says, is a disinfectant approved by the Indian Council of Medical Research (ICMR), and studies have shown that it is safe for use on skin and surfaces. The Sugaradhana Antimicrobial Disinfectant solution, it adds, was tested as per the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. It was found to be safe for the skin with no side effects and certified by Radiant Research and other organic government bodies, the company states.

How is the spraying operation carried out and for how long?

An American Champion Scout two-seater aircraft will be used for the spraying. In an hour of operation, the aircraft can spray 1,000 litres of disinfectants over an area of 300 hectares. The aircraft will return to the Jakkur aerodrome every 20 minutes for refuelling.