'Well known' that viruses can travel and spread through the air, says professor

Margaret Harris of the WHO says the possibility of Covid-19 spreading in crowded or poorly ventilated areas cannot be ruled out. Picture: Leah Farrell/RollingNews.ie

The World Health Organisation (WHO) has acknowledged evidence that coronavirus can be spread by tiny particles suspended in the air.

An official says airborne transmission cannot be ruled out in crowded, closed or poorly ventilated settings.

If the evidence is confirmed it may affect guidelines for indoor spaces.

An open letter from more than 200 scientists has accused the WHO of underestimating airborne transmission.

Margaret Harris of the WHO says the possibility of it spreading in crowded or poorly ventilated areas cannot be ruled out.

"That is why many countries have been asking people to wear masks when they are on public transport, places where it is difficult to ventilate or in enclosed spaces such as shops to minimise the possibility of transmission."

Professor John Wenger from UCC is one of the more than 200 scientists who has signed the open letter.

He said the previous SARS disease had been an airborne one.

It is well known that these viruses can travel through the air and spread this way.

Prof Wenger said a large body of evidence shows that exhaled breath releases smaller particles that can travel further and remain in an indoor environment for a few hours and this could be an important transmission route under certain conditions, such as in crowded or poorly ventilated areas.

He suggested adding extra measures such as avoiding high room occupancy, spending a prolonged amount of time indoors - unless wearing a mask - and increasing ventilation.

He says better ventilation and more use of face masks in indoor settings would help stop the spread.

The WHO has not really covered ventilation, said Prof. Wenger.

Simple steps such as opening doors and windows could be useful and should be considered when schools and offices return to work.

"Ventilation in the home is useful, we need to make sure we have properly ventilated workplaces and schools in fact."

There are now more than 11 million cases and 500,000 deaths linked to Covid-19 globally.

Dr Mike Ryan, executive director of the WHO, fears there could be a sharp increase in coronavirus fatalities in the coming weeks.

"What we have seen in the month of June is an acceleration in the number of cases and what has not accelerated with that is the number of deaths "But we know that it takes time and there is a lag phase.

"Some of this may be lag, we may see deaths start to climb again because we have only really experienced this rapid increase in cases over the last five to six weeks."