A scientist who advises the Government suggested schools should unseal windows painted shut to reduce the transmission of Covid.
Professor Calum Semple, a member of the Scientific Advisory Group for Emergencies [Sage], said he was not a “great fan” of young children wearing face masks.
Instead, he said improving ventilation such as unsealing windows would be a “more effective” way to reduce transmission.
Speaking in a personal capacity, he told BBC Radio 4’s Today programme: "Primary school children are the lowest risk both to themselves and to society.
"There is really good data coming out...that show that children are half as likely to acquire the virus to a third as likely to acquire the virus.
"When it comes to transmitting, again, they are probably half as likely to transmit it as adults. That risk actually gets smaller as you go into younger age groups. So, I am not a great fan of young children wearing face masks.
“Certainly, older primary school children probably are able to wear a mask quite well.
"But if I had to invest in a single activity to improve the environment both for the children and the adults, I’d be looking at improving the ventilation, unsealing windows that have been painted shut and kept shut for energy-saving reasons.
"That would be a much more effective way to reduce transmission in schools."
It comes amid a row over whether children should wear face masks when they all return to school in full from March 8.
The Government has announced measures to enhance Covid safety, including twice-weekly testing for secondary pupils and a recommendation to wear face coverings in classrooms.
However, teachers warn that the wearing of facemasks will not be enforceable and have complained about confusion from Government.
Some heads had already written to parents telling them masks would be mandatory before Schools Minister Nick Gibb said during interviews yesterday that they were not compulsory and it was up to parents to decide.
“We’re recommending very strongly to schools that there should be face masks in the classroom, particularly when you can’t socially distance in that classroom,” he told Good Morning Britain.