Before we had vaccines, there were few if any weapons in the fight against Covid-19. But there was one that could at least help reduce your risk of picking up the virus — fresh air.
According to research released late last year by the government’s Scientific Advisory Group for Emergencies (SAGE), a well-ventilated room can clear 70 per cent of virus particles in the air — leading to official advice to either open windows regularly for 15 minutes at a time or leave them open a little, continuously.
And now — as we’re starting to socialise indoors once more — a panel of experts is calling for a transformation in the quality of air inside buildings, including our homes.
Before we had vaccines, there were few if any weapons in the fight against Covid-19. But there was one that could at least help reduce your risk of picking up the virus — fresh air
In an article published in the journal Science last week, the panel of 39 researchers from 14 countries, including the UK, says the quality of our indoor air should be monitored to the same standards as food and water to protect against the transmission of disease.
‘We all want to be confident the air in our homes and the buildings and restaurants we visit is clean, just as we are assured the water coming out of our taps is safe to drink,’ said Dr Julian Tang, a clinical virologist at the University of Leicester, and one of the report’s authors.
The experts are calling for indoor air quality standards to be agreed and enforced by governments and for monitors to display the quality of air on public buildings.
They argue this could not only help to prevent future pandemics, but also slow the spread of other airborne diseases such as flu and colds.
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‘This is particularly relevant given the emergence of new Covid variants that may be more easily transmissible: by taking steps to improve ventilation now, we can try to stop a fresh wave taking hold,’ says Catherine Noakes, a professor of environmental engineering for buildings at the University of Leeds, and another of the report’s authors. Yet many of us don’t seem to have got the message.
The experts are calling for indoor air quality standards to be agreed and enforced by governments and for monitors to display the quality of air on public buildings
‘Data suggests that most people think ventilation is less important than ‘Hands, Face, Space’, but in many ways ventilation is the most important thing,’ adds Stephen Reicher, a professor of psychology at the University of St Andrews, and a member of SAGE.
In fact, the science now shows the coronavirus is far more likely to be transmitted through the air in droplets or smaller particles called aerosols than, for example, via infected surfaces.
‘We know these aerosols behave in a similar way to smoke but are invisible — and the majority of virus transmissions happen indoors,’ says Professor Noakes.
‘Being indoors with someone infected, with no fresh air, the particles can remain in the air for hours and build up over time.’
She says there are simple everyday measures we can adopt at home or in shops and offices — in particular opening a window for ten to 15 minutes every couple of hours.
The crucial role played by the flow of indoor air in Covid transmission was underlined in Western Australia, where the government recently closed a third of its quarantine hotels following an outbreak in January.
Investigations showed the virus had escaped from the room of an infected person in quarantine via a gap under the door, travelling down the corridor where it infected a security guard whose post was several rooms away.
So why do we pay such little attention to ventilating our buildings properly?
‘We’ve developed a culture of ‘airlock’, particularly in our air-conditioned, central-heated offices, where either no one thinks to open a window or it’s not possible to open them,’ Trish Greenhalgh, a professor of primary care at the University of Oxford, told Good Health.
Our drive to make our homes more energy efficient has been at the expense of good ventilation — ‘it often never occurs to people to open the windows because they’re worried about letting heat out’, adds Professor Noakes.
But with gyms and indoor dining back on the agenda, the importance of fresh air in confined spaces where people talk loudly or breathe more deeply is clear.
‘This is particularly true as evidence shows that ‘superspreaders’ — people who are able to spread the disease to a disproportionately large number of others — do this in enclosed indoor spaces such as pubs,’ says Professor Noakes.
With many offices also preparing to return to near-normal business, the quality of fresh air in workspaces also needs to be addressed, experts say. Safety standards currently require employers to ensure there’s an ‘adequate supply’ of fresh air for workers in enclosed spaces, but it’s left to the business to decide how to provide this.
‘You see many businesses advertising their cleaning and sanitising measures — but they’d do better to focus on making sure that the air is clean and fresh,’ says Professor Noakes.
‘If a business has a mechanical ventilation system, ensure it’s working correctly. If not, consider which windows and doors you can open to allow fresh air into the building and brief your employees on ensuring that this is done.
‘You might find that an air cleaner is also useful in a single room or enclosed space.’
Portable air purifiers or cleaners filter impurities out of the air around them — and some work with ultraviolet light to destroy bacteria and mould particles.
‘Air purifiers can be helpful in a localised area but there’s a very broad range out there of variable efficiency, so shop around,’ says Professor Noakes.
Although attention is on preventing circulating viruses, experts say better ventilation could have wider benefits — from improved sleep to reduced absenteeism from work and schools.
One of the chief issues with poor air flow in any building is that it allows indoor air pollution to build up. This consists of gases such as nitrogen dioxide and carbon monoxide and particulate matter (PM), for example, soot and dust.
The sources range from gas cookers and central heating to chemicals found in cleaning and personal care products, adhesives, paints and cigarette smoke.
These can contribute to a range of lung diseases including chronic obstructive pulmonary disease (COPD), a group of progressive lung diseases such as emphysema and asthma.
There’s also evidence air pollution causes damage to your heart and circulation by affecting the inside wall of blood vessels, causing them to become narrower and harder.
‘We spend 90 per cent of our time indoors where the concentration of some pollutants can be up to five times higher than outdoors,’ says Hasan Arshad, a professor of allergy and clinical immunology at the University of Southampton.
Meanwhile, the benefits of improving ventilation are numerous. ‘There’s even evidence it helps you to sleep better — and to perform better the next day as a result,’ says Professor Noakes.
This is thought to be because the carbon dioxide we breathe out can build up in a sealed room, making us sluggish and drowsy.
Levels of carbon dioxide are measured in parts per million (PPM), with a well-ventilated indoor space being generally accepted to have 800 to 1,000PPM. But with the windows shut, carbon dioxide levels in bedrooms can rise to 2,500PPM and above.
New-build houses and offices are increasingly being fitted with MVHR systems (short for mechanical ventilation with heat recovery), which draw air in from the outside, filter it to remove many pollutants, while retaining heat, and then distribute it around the home.
However, they are not required to be installed by law and are difficult to fit in existing houses.
Professor Noakes wants people to get into the habit of opening windows (and using extractor fans) for brief intervals throughout the day — especially when they cook or use chemicals such as aerosols.
‘It’s also a good idea to make an effort to reduce the amount of chemicals you use at home in general,’ she adds. ‘Limit the aerosols you use — swap a spray-on deodorant for a roll-on for instance, or try to use much less of a product.
‘Now is the time to apply the lessons we have learned from Covid-19 — and to look at the ways we can transform our indoor air.’
