After the screaming headlines and point-scoring in the political battle over the full reopening of schools, theres a quiet, serious new reality for teachers and teaching assistants: spending every day in a workplace where they may be worried or scared about the risks of infection.

Plenty of teachers will be turning over questions throughout the day: is that trip beyond your bubble to the loo a bit dicey? Could the novel coronavirus be lurking in a pupils well-thumbed Dickens novel?

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The science of school closures:An overview for schools

Should teachers wear face masks?A professor of public health gives her view

Coronavirus:Can childrensocially distance?

One of the big unknowns about the coronavirus, where research is yet to reach a consensus, is whether children have a significant role in transmission or a minimal one. But scientists do agree on other aspects of how the virus is transmitted, shedding light on which areas of a school might present the highest risks and on how schools might mitigate those risks.

When we speak, cough, sneeze and breath, we produce droplets that are of respirable/inhalable size, small droplets known as aerosol, and also much larger dropletsthat are even larger than the diameter of a human hair, explains Jonathan Reid, professor of physical chemistry at the University of Bristol and an expert on aerosols.

The larger droplets fall quickly to the ground in a few seconds and could contaminate surfaces, offering an indirect, but important way viruses are transmitted, he adds.

Then theres the risk of being directly exposed to larger droplets when someone sneezes or coughs if they are standing nearby, hence physical distancing guidance.

But theres also a question over whether infection can take place via those small aerosol particles, which can remain suspended in the air for many minutes or even hours. Given the difficulties in persuading primary school children, in particular, to distance from each other or from staff perhaps more like impossibilities the question could be a pressing one for schools.

One study, led by researchers from the US National Institute of Allergy and Infectious Diseases and published in a brief summary in the New England Journal of Medicine, says its results suggest that novel coronavirus transmission via aerosol and surfaces is plausible. Researchersfound that the virus can remain viable and infectious in aerosols for hours and on surfaces up to days.

However, that research took place in lab rather than real-life conditions; plenty of scientists think that the evidence on aerosol transmission is inconclusive at present. Reid is attempting to offer more definitive answers in a study.

Which areas of a school does Reid think might present the highest risk of infection? I would say anywhere that is unventilated or poorly ventilated, has a high throughput of people or where there can be contaminated surfaces or poor hygiene so, for example, toilets, he replies.

Lawrence Young, a virologist and a professor of molecular oncology at the University of Warwick, agrees: Any indoor environment where there is poor ventilation is a risk for transmission. This would be exacerbated by having many individuals walking through an area like a corridor or communal area. Social distancing in these areas is essential.

Peter Collignon, an infectious diseases physician and microbiologist at Canberra Hospital and a professor at the Australian National University, says that in a school the key means of potential virus transmission are teachers and parents, making staffrooms and indoor meetings with parents the riskiest areas.

He suggests limiting staffroom numbers to allow for social distancing and trying to be outdoors more than indoors in general.

Many schools are utilising outdoor spaces whenever they can. But rainy spells and winter will bring the need to manage increased use of corridors and communal areas.

When it comes to viruses survival on surfaces, one authority is Bill Keevil, professor of environmental healthcare at the University of Southampton. His research has found that the coronavirus that causes the common cold, which he describes as structurally almost identical to the new virus, survived at least five days on stainless steel, glass, plastics, ceramics.

Similarly, the New England Journal of Medicine study found the novel coronavirus was detected on plastic after 72 hours but could not be found on cardboard after 24 hours.

So perhaps plastic desktops should be a focus for cleaning, with book covers less of a concern for long-lasting infection risk.

Should school staff be worried if they touch a door handle and forget to wash their hands afterwards?

I would be, because Im a microbiologist, Professor Keevil replies, none too reassuringly. Humans, were very tactile. We continually touch our faces, eyes, nose and mouth anything from 15 to 30 times an hour.

The highest-risk surfaces would be the obvious touch ones, he adds: door handles and push plates, stair rails and toilet areas, particularly for younger children.

However, other researchers point to reasons not to cower in fear before every surface.

Dont panic, says Collignon of the risks of touching a door handle. Being close to someone inside with a cough for over 15 minutes is very much higher risk. But use hand sanitisers before touching your face or eating.

In response to the 72-hour figure for the virus survival on plastic found by the New England Journal of Medicine study, Johns Hopkins University professor of cell biology Carolyn Machamer has noted that just 0.1 per cent of the virus material remains after that time, making infection unlikely.

She has told the Johns Hopkins website that people are more likely to catch the infection through the air if you are next to someone infected than off of a surface. Cleaning surfaces with disinfectant or soap is very effective because once the oily surface coat of the virus is disabled, there is no way the virus can infect a host cell.

And perhaps there is another solution for schools on surfaces. Keevil has been studying the antimicrobial effects of copper for 20 years, with his research on other coronaviruses finding that they were inactivated in minutes when they came into contact with such surfaces.

If you enjoy the idea of the coronavirus taking a beating, then savour Keevils description of how macho-sounding copper ions can punch holes in the cell membrane of a bacterium or virus, allowing the ions to flood into the cell, inhibit the respiration of bacteria then destroy DNA and RNA in both bacteria and viruses, which means there is no chance of mutation and resistance.

He highlights a Greek study that found reduced rates of respiratory infections in schools where copper alloys were used to cover or replace surfaces such as stair rails.

Surfaces can be coated in copper, Keevil says, so rather than have to completely rekit schools in solid copper alloysas an interim, you can go in and cover them.

Aside from such potential innovations, the best options for schools at present seem to lie in ventilation, physical distancing (or attempts at it)and, of course, routine and frequent cleaning.

But theres plenty above for school staff to consider while weighing up a trip to the socially distanced staffroom. Just make sure you dont touch your face while youre thinking about it.

John Morgan is a freelance journalist

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Covid-19: What's the most infectious place in school? - TES News