How buildings can fight coronavirus

A Harvard University professor writing in the Financial Times outlined why building ventilation systems could be either a blessing or a curse in the effort to contain the coronavirus.

In his opinion piece ‘How healthy buildings can help us fight coronavirus’, Joseph Allen called for an urgent review of how buildings are ventilated. He pointed out that, just as buildings can make things worse, they can also make things better.

The co-author of ‘Healthy Buildings’, recalled how the global transmission of SARS in 2003 was triggered by one person, in one room on one floor of a hotel in Hong Kong. The building amplified this single source of contamination, transmitted it to 16 other people, who then proceeded to distribute it around the world.

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The good news, according to the professor, is that it is “quite easy to improve filtration and ventilation in most buildings…and increase rates of fresh air…we should adjust indoor humidity levels and avoid overcrowding.”

Increasing ventilation and filtration rates “above industry minimums” reduces the risk of virus transmission by 50%, according to Professor Allen. He believes that most buildings are using “cheap filters” that capture less than 20% of airborne virus-sized particles and by improving these it would be possible to capture more than 80%. He called for wider use of portable air purifiers with high efficiency particulate filters – especially in schools.

We have a growing expert group at BESA looking at the expanding issue of health & wellbeing in buildings – and the links between indoor air quality (IAQ) and health. They welcomed the professor’s conclusions, but said ventilation engineers and maintainers must go further to deliver the right amount of air changes per hour not just minimum ventilation rates.

“As well as providing good quality filters, assessed to the international performance standard (ISO16890), we should also be using proven clean air technologies,” said the group’s chair Nathan Wood. “Air quality monitoring is also a readily available and affordable technology, which can be paired with basic ventilation products via the internet of things to create smart systems that can respond to changing conditions.”

Professor Allen also highlighted the importance of managing humidity. He said some viruses survive best when relative humidity (RH) is low – so there is a role for humidifiers. For example, his research team discovered that increasing RH to between 30 and 50% led to a 32% drop in influenza virus survival. Early results appear to show that the coronavirus survives better on surfaces when RH is 20% and does less well at 50%.

A report last month from the Royal College of Paediatrics and Child Health (RCPCH) and the Royal College of Physicians (RCP) also pinpointed a direct correlation between poor IAQ and damage to children’s health.

It found that IAQ is often between five and 13 times more polluted than outdoor air due to a combination of sunlight, contamination sources from outdoors mixing with airborne chemicals, particulates and viruses generated inside the building. It added that children spend, on average, just 68 minutes a day outside making the threat to their wellbeing overwhelmingly an indoor issue.

The government does seem to have air pollution, in general, in its sights as evidenced by the recent decision to bring forward the banning of diesel cars to 2035. We also hope that the current review of Part F of the Building Regulations and the Future Homes standard will embed higher quality ventilation in future planning rules.

However, in the meantime, the threat to human health posed by indoor pollution is an immediate one. This is not something that can wait for a policy change in 15 years’ time – and the present threat from coronavirus should be the ultimate wake-up call.

In any case, tackling IAQ is a lot more straightforward than cleaning up polluted outdoor air as it involves a series of well understood (relatively inexpensive) measures to improve the performance of filtration, ventilation and air cleaning – so that the building becomes a ‘safe haven’ from what is going on outside.

However, tackling internal transmission of disease does involve careful thought.

The addition of air cleaning technology should be considered by any ‘at risk’ buildings – particularly healthcare facilities – to supplement good ventilation strategies. We should be using ULPA filters to remove virus sized particles and all ventilation filters should be maintained if they are not to become sources of contamination themselves.

Ventilation ductwork should be checked and cleaned if necessary. Managers of at risk buildings should also consider additional measures like ultra violet cleaners to supplement the filters.

“Viruses attach to particulate matter in the air and when they hit a filter, they break up. Some stick to the filters, others get trapped in the membrane and some get through,” said BESA group member Richard Greenwood of Radic8. “Filters allow time for other technologies such as UV radiation to destroy the DNA of viruses.”

The Health & Wellbeing in Buildings group also stressed the importance of the direction and height of air flow – a factor that tends to get overlooked. “Having clean air technology that drags contaminated air to the ground and keeps pathogens from being kicked up into the air is very important,” said Mr Greenwood. “Ideally you want to create a laminar air flow in order to distribute clean air and collect polluted air as efficiently as possible.”

We believe the government should also give local authorities the power to compel building owners and managers to carry out IAQ checks immediately and put measures in place for all premises used by the public including schools, hospitals, and commercial offices etc.

As an industry, we have been arguing for these measures for some time, but there is nothing like the threat of a looming pandemic to focus minds.

David Frise is chief executive officer of the Building Engineering Services Association (BESA)