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Facilities in Japan cautioned against hypochlorous acid misting to fight COVID-19

A hypochlorous acid solution atomization device introduced in April is seen on a community bus in Tochigi Prefecture. (Photo courtesy of the Tochigi Municipal Government)

An increasing number of facilities in Japan are suspending use of devices to atomize hypochlorous acid solution as a disinfectant, which has been commonly been adopted by schools, day cares and public facilities to prevent the spread of the novel coronavirus, following a government call for caution.

On May 29, the Ministry of Economy, Trade and Industry (METI) introduced guidance from the World Health Organization (WHO) stating that in indoor spaces, "routine application of disinfectants to environmental surfaces by spraying or fogging (also known as fumigation or misting) is not recommended for COVID-19."

The Wakayama Prefecture town of Kushimoto in western Japan, has placed humidifiers at the entrances of all elementary and junior high schools in the town, and had also planned to spray hypochlorous acid solutions when schools reopened on June 1. But it refrained from doing so following the METI announcement, and is said to be undecided on what it will be used for in the future.

Hypochlorous acid solutions are made through electrolysis of hydrochloric acid or saltwater solutions. More people have been buying them in place of alcohol disinfectants, which are in short supply. METI is still evaluating the effectiveness of the solutions as a disinfectant on object surfaces contaminated with viruses. But misting of the solutions is not recommended in terms of effectiveness or safety.

The Ministry of Heath, Labor and Welfare's Tuberculosis and Infectious Diseases Control Division stated, "Even if it was effective on objects, misting is not effective, and could be harmful depending on the concentration." Nevertheless, more businesses and local bodies have been testing hypochlorous acid solution aerosol disinfection. Fogging equipment has been introduced by a host of facilities including stores, offices, and welfare facilities, as well as by public transport operators, day care centers, after-school child care facilities, government offices, schools and the like.

The Kanagawa Prefecture city of Ebina south of the capital had installed a humidifier producing a hypochlorous acid mist at the city hall counter in March. But it stopped using it on June 1. "It was to relieve residents' concerns. We're confirming its safety with the supplier," a representative of the city's health promotion division said.

The city has continued to provide hypochlorous acid solutions to residents free of charge, but said it would revise a notice of caution to state that use of the solution is limited to disinfection of objects, and advise against its use in humidifiers or as a hand sanitizer.

However, not all misting equipment has been taken out of use. The city of Hasuda in Saitama Prefecture, north of Tokyo, halted the use of humidifiers at the entrance of the city hall and at the fire department headquarters, saying it was aware of information that misting should be avoided. But it continues to use humidifiers at the entrances of elementary and junior high schools and in classrooms. A representative of the city's school education division commented, "We'll make sure they aren't used for long periods, and have schools continue to utilize them while ensuring there is no direct contact with the skin. We'll suspend their use if any students complain about feeling unwell."

Meanwhile the city of Tochigi, further north of the capital, continues to use misting equipment on two community buses, saying that it had heard from their manufacturer that they posed no threat to people's health.

At private firms there have been some moves to suspend use of the equipment, and some restaurants and transportation operators have announced on social media and their websites that use of mist equipment would be suspended.

A METI representative commented, "Many specialized institutions do not recommend using misting for people, and just as the WHO says, one can only imagine there is some kind of demerit in inhaling disinfectants. The costs are also high so we'd like people to make decisions with care."

In the future the health ministry is also considering sending out a notice with new recommendations on aerosol disinfection with hypochlorous acid solutions and other such measures.

(Japanese original by Shuji Ozaki, Regional News Department)

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