The spraying should only be done in narrowed spaces where Covid-19 cases have been detected, and the amount of chemicals used must be controlled to ensure safety for human beings as well as the environment.

"Do not apply the method of spraying chemicals and germicidal preparations on people in any situation, including using a device to spray these directly on people or inside a disinfection chamber," said a Monday statement issued by the ministry.

Some localities have sprayed disinfectants in public places to prevent the spread of the new coronavirus.

Some agencies and companies have established disinfection chambers while others have used disinfectant sprayers directly on people sent to centralized quarantine camps.

However, the World Health Organization (WHO) has said it does not recommend the spraying of disinfectants outdoors because it can affect both the sprayer and the people around.

The U.S. Centers for Disease Control and Prevention (CDC) shares this view.

"The use of large quantities of germicidal chemicals for outdoor spraying can also harm the environment and waste chemical reserves to be used for pandemic prevention," the ministry said.

At the end of July, six tons of Chloramin B mixed with water at the rate of 0.5 percent was sprayed across HCMC.

Last week, 180 officers and military personnel were mobilized to spray the disinfectant in seven Hanoi districts.

So far in the ongoing wave that broke out in late April, Vietnam has registered more than 153,600 Covid-19 cases, with HCMC accounting for almost 96,300.