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MANY more people in the UK are returning to their workplaces as coronavirus lockdowns ease. Some US companies are also attempting a return: Google is allowing workers to return on a voluntary basis, for instance. More will do so in coming months. Returning safely will involve a mix of strict measures and tailored arrangements to make employees feel safe and happy. 鈥淚t鈥檚 not a one-size-fits-all problem,鈥� says Michael Tildesley at the University of Warwick, UK.

From 12 April, , including all shops, hairdressers and libraries. UK prime minister Boris Johnson has argued that most people will return to their workplaces full-time and that there won鈥檛 be a permanent shift towards working from home.

With more than in the UK in the past week, there are risks associated with going back to the workplace. It may not cause many additional deaths 鈥� because almost half of the population has received at least one dose of a vaccine, including the majority of those who are most vulnerable 鈥� but it will raise the number of cases. That increase has two consequences. First, 1 in 10 infected people seem to develop long covid, which can include exhaustion and concentration problems. Second, more cases means more opportunities for the virus to mutate to become more dangerous.

The risk of transmission of SARS-CoV-2, which causes covid-19, needs to be reduced as much as possible in the workplace, says Lisa Lee at Virginia Tech in Blacksburg.

The key to this is to follow an established risk management strategy called the , says Catherine Noakes at the University of Leeds, UK. This involves doing the most effective things first, and only using less effective strategies as a fallback.

Approaches that are built in and happen automatically are the most effective, while the least effective are those that rely on people changing their behaviour. 鈥淭he least reliable intervention is the one that depends on people,鈥� says Lee.

The most effective strategy is elimination, in which the hazard simply isn鈥檛 present. However, outside countries like New Zealand that have pursued zero-covid strategies, workplaces can鈥檛 hope to be entirely covid-free.

The next best step is substitution, where the aim is to replace the hazard with something safer. That can mean swapping a toxic chemical for a non-toxic one. We can鈥檛 swap the coronavirus for another virus, but because the hazard at work is due to spread by people, employers can instead substitute different practices to make being in the workplace less risky. 鈥淲e can have people working in bubbles so there are less of them [in the office],鈥� says Noakes. 鈥淲e can take away activities we know are high risk, like meetings in meeting rooms.鈥� These strategies are surprisingly powerful, she says.

The next step is engineering defences against the hazard. In this case, ventilation is key. There is strong evidence that poorly ventilated indoor spaces are the worst for viral transmission. SARS-CoV-2 spreads through air in two ways: in large droplets produced when someone coughs or sneezes, and in smaller droplets known as aerosols that can linger in the air and transmit the virus across distances greater than 2 metres. Improving ventilation makes a huge difference. The key is for all the air in the room to be replaced several times an hour, so the virus can鈥檛 build up.

Unfortunately, there is no easy way to tell if a space is well ventilated, says Lidia Morawska at the Queensland University of Technology in Australia. She has been using carbon dioxide levels as a proxy for the virus to study possible transmission around her office and nearby restaurants. The bigger the build-up of CO₂, the less ventilation. 鈥淏ased on my visual assessment of the size of the venue, number of people and airflow created by natural or mechanical ventilation, I would have said that spaces were sufficiently ventilated,鈥� she says. But measuring CO₂ showed this wasn鈥檛 the case in numerous places. Instead, CO₂ levels often reached several thousand parts per million, meaning air wasn鈥檛 being replaced fast enough to clear the gas or virus particles.

Improving ventilation isn鈥檛 just a matter of opening windows. It requires specialist engineers, and can be difficult and expensive. But it has benefits beyond reducing the risk of covid-19. Excessive CO₂ is harmful, and better ventilation reduces indoor air pollution.

Air purifiers that remove the virus from the air may help if carefully chosen, says Noakes.

Kirsty Buising at the Royal Melbourne Hospital in Australia and her colleagues have looked at the effectiveness of air purifiers in clearing aerosols from wards that had been used for people with covid-19. In a published on 31 March, they show that two portable air purifiers cleared 99 per cent of artificial aerosols from a hospital room in 5.5 minutes (MedRxiv, ). Although they identified a link between airflow on the ward and the spread of covid-19 infections, no one has yet confirmed that such devices actually trap SARS-CoV-2, says Noakes, it is just assumed they will, based on the size of particles they catch.

鈥淭he least reliable intervention is the one that depends on people changing their behaviour鈥�

Instead of tackling air flow issues, many businesses 鈥渟tick a load of Plexiglas up鈥�, says Noakes. Unfortunately, screens are only really useful for short-term encounters, such as protecting shop assistants during transactions. That is because they mainly stop large droplets. Given time, the smaller aerosols can drift around them. For people sitting for hours in an office with good physical distancing, adding barriers makes no difference, but better ventilation would.

The fourth phase of control is administration. This means changing how people behave and is inherently less effective. It can entail, for instance, creating one-way systems by putting sticky tape on the office floor. 鈥淵ou have to be careful not to get obsessive over it, but it does provide a visual reminder of 鈥業 mustn鈥檛 get too close鈥�,鈥� says Noakes.

The least effective method, and therefore the last resort, is personal protective equipment like face masks. These reduce the chance that an infected person will spread the virus, but they can be uncomfortable, people must take them off to eat and drink, and not everyone can wear them. Still, they are better than nothing, says Lee.

Both Lee and Noakes say that businesses are making changes, but in the UK and the US they are doing so largely without funding from governments, and often on the basis of guidelines rather than legally binding regulations. That means efforts tend to focus on cheap but weak solutions, like changing people鈥檚 behaviour, but not on ventilation, which is effective but difficult.

There is still too much focus on cleaning surfaces, even though it is now clear that the virus spreads mainly through the air, says Teresa Moreno at the Institute of Environmental Assessment and Water Research in Barcelona, Spain. 鈥淐ompared with air, the surface is not the problem.鈥� The World Health Organization (WHO) needs to hammer that message home, she says.

Morawska also wants more explicit guidance on ventilation standards. 鈥淭he problem is that at the moment, there are no existing standards applicable to respiratory infection control in public spaces, including workplaces,鈥� she says. Her team has developed an , and she wants to see such tools included in guidelines from the WHO and governments.

Risk of commuting

It isn鈥檛 just the workplace itself that needs to be made safe. People have to commute, and that can mean getting onto buses or trains.

Crowded public transport may cause anxiety (see 鈥淲hy going back to offices may affect mental health鈥�), but in reality, it is likely to be fairly low risk. Moreno and her colleagues looked for SARS-CoV-2 on buses and subway trains in Barcelona between May and June 2020. They , but the risk of infection was low, and that was before most people started wearing masks.

Most people sit quietly and don鈥檛 stay in the same vehicle for more than an hour, and buses and overground trains are often well ventilated, as are subway trains. What鈥檚 more, staggered working hours limits overcrowding on platforms. Shared journeys in cars, however, are riskier because ceilings are lower.

People also have to get lunch, and may socialise after work. To make it easier to maintain social distancing, the French government recently scrapped a law banning people eating at their desks. 鈥淚t鈥檚 the social interactions that go with going back to the office that are probably more risky than the office,鈥� says Noakes. 鈥淚n the workplace, it鈥檚 been organised in a particular way and you comply with the rules. Whereas it鈥檚 very easy the minute you leave the door to slip slightly.鈥�

Employers need to ask themselves three questions before they bring someone back into the workplace, says Ben Willmott, head of public policy at the Chartered Institute of Personnel and Development (CIPD) in London. First, is it essential that the person come in? Second, is it sufficiently safe? And crucially, is it mutually agreed?

Despite what Johnson says, many businesses and workers aren鈥檛 going to go back to how things were, says Willmott. In a report published in September 2020, the CIPD surveyed UK employers and found they expect 37 per cent of their workforce to work from home regularly after the pandemic is over, compared with 18 per cent before. In a published this month, the CIPD found that 63 per cent of employers plan to introduce or expand hybrid working.

鈥淲e鈥檙e not just talking about flexible location,鈥� says Willmott. That risks creating a two-tier workforce, where people whose jobs cannot be done remotely have no flexibility. 鈥淵ou鈥檝e really got to think about flexible hours as well. Things like annualised hours, term-time working, job share, part-time or flexi-time, compressed hours.鈥�

Many people want to keep working flexibly. People with disabilities have long demanded the right to do so, says Anna Morell at Disability Rights UK, as have parents and others who care for vulnerable people. 鈥淲e want people to be able to choose what they feel is safest for them,鈥� says Morell. The lockdowns showed that people can be productive from home. 鈥淚t鈥檚 really important that that flexibility is maintained if people need that,鈥� says Morell.

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