Engineers’ report says proper building ventilation crucial to control Covid

THE Royal Academy of Engineering (RAEng), along with partners including IChemE, have released a report saying that improved ventilation in buildings and public spaces is crucial in controlling Covid-19.

Proper ventilation can help to mitigate the risks associated with Covid-19 by diluting virus particles in the area as well as removing them from the building. An adequate supply of outdoor air should be supplied to an indoor space. This can be done via natural means such as opening windows, or mechanical means such as ducts and fans.

The Government Chief Scientific Adviser, Sir Patrick Vallance, commissioned the report and asked for a rapid review of actions needed to make infrastructure resilient in terms of infection control. This includes what needs to be done ahead of winter 2021/2022 to reduce the risk of Covid-19 transmission, as well as how buildings can be redesigned and retrofitted for future resilience.

The report, Infection Resilient Environments: Buildings that keep us healthy and safe, says that the importance of ventilation in public and commercial buildings, as well as transport systems, is often neglected and that the pandemic has revealed flaws in the design, management, and operations of buildings. These flaws need to be addressed for management of the pandemic and future pandemics, as otherwise society will incur high financial and health costs.

It notes that with the removal of restrictions in England on 19 July, the importance of infection control in building and transport management will increase. The changes that need to be made will be beneficial well beyond Covid-19.

The report was compiled by a National Engineering Policy Centre working group led by RAEng and the Chartered Institution of Building Services Engineers (CIBSE), with input from IChemE, the Institution of Mechanical Engineers, and the Institution of Civil Engineers.

Assessing risks

The Government and professional bodies need to provide clear and consistent communication on ventilation to assist building owners and operators with managing the risk of infection, according to the report. Adequate ventilation needs to be prioritised alongside measures such as cleaning and distancing, and measures need to be identified to implement this at moderate cost.

The authors note that there is a great variation in understanding regarding infection control measures, with some companies prioritising ventilation to the point of almost completely ceasing surface cleaning, whereas others remain focused on cleaning and give little attention to ventilation.

There are currently skills and knowledge gaps which need to be addressed through training, re-skilling, and recruitment. Investment will also need to be made for R&D on topics such as the acceptable minimum ventilation standards.

Currently, the quality of ventilation is difficult to assess. A participant in the evidentiary hearings conducted for the report said: “I don’t know what good ventilation is. I’ve had litres a second per person, I’ve had air changes per hour, I’ve had litres/second/square metre as benchmarks that we could use.” This also has the effect that people are more likely to feel reassured by constant cleaning rather than a ventilation system that they can’t see or isn’t clearly understood.

The risk profile that building operators face has changed with Covid-19. Regulation is based on risks, but prior to the pandemic there was little emphasis on the importance of ventilation for mitigating infections. There is a need to develop detailed guides to help build a shared understanding of standards that is required for regulation to be effective.

The report notes that Building a Safer Future – the review led by Dame Judith Hackitt –revealed endemic quality issues in the built environment that are just as relevant for air quality as to fire safety.

The report also emphasises the importance of continuing the effort to cut CO₂ emissions from buildings simultaneously with improving infection control.

The report makes some key recommendations, namely that the Government needs to: identify skills requirements and address the skills gaps; undertake a rapid review on the capability of regulators to enforce buildings standards in relation to public health; work with research institutions to address key research gaps; commission R&D to fill knowledge gaps; and meet net zero targets while addressing infection control.

R&D and technological solutions

Several areas are identified that need further research, including understanding aerosol transmission for different types of buildings; assessing the effectiveness of potential technology solutions including air cleaning devices; and understanding potential airborne infection risks associated with plumbing, drainage, and hand dryers.

It also warns that an uninformed reliance on technology can have negative consequences, and that the benefits of some air-cleaning devices are unclear. The main types of technology in use such as high efficiency particulate air (HEPA) filters and ultraviolet light are likely to reduce transmission in areas where ventilation is difficult. However, the role of other technologies such as ionisers, plasma, chemical oxidation, photocatalytic oxidation and electrostatic precipitation is less clear and some have been associated with secondary pollutants that may cause respiratory and skin irritation.

CO₂ monitors could be used to give an indication of the level of fresh air in a building, as the level of CO₂ is related to ventilation quality and is therefore linked to risk of airborne transmission. These would be most effective in small spaces with multiple occupants.

On potential surface transmission the report says that the choice of material can make cleaning easier and that materials like silver and copper can inactivate respiratory viruses. There are also antimicrobial coatings that could be used on certain surfaces, and no-touch technologies could help for touch points such as door and lift buttons. However, it cautions that more research will be needed to assess whether anti-microbial products could lead to anti-microbial resistance.

Peter Guthrie, RAEng VP and Chair of the NEPC Infection Resilient Environments Working Group, said: “We must take action now to make sure that good practice in ventilation is widely understood and applied across workplaces and public buildings.

“Longer term, this is a real opportunity to transform the way we design and manage our buildings to create good, healthy and sustainable environments for those who use them. We must also integrate this with thinking on infection control into our approach to net zero, to prevent inadvertently hard-wiring a susceptibility to infection and other health risks into our building stock and management practices.”

Claire MacLeod, IChemE Learned Society Committee member and Subject Area Lead for Health and Wellbeing, said: “From a chemical engineering perspective, transmission of a virus is a process, and Covid-19 should be managed like any other process hazard. Chemical and process engineers are expertly placed to support the much-needed development of technical guidance on measures to manage infection risk within buildings while maintaining thermal comfort and energy efficiency, and look forward to working with our partners to do so.

“Volunteer members of the IChemE Covid-19 Response Team working in partnership with the International Society for Pharmaceutical Engineering UK Affiliate (ISPE) have redeployed risk assessment methodology developed for use in the process industry as a management tool to reduce the risk of infection in workplace settings, highlighting how chemical and process engineers are utilising their specialist skills to support the response to the pandemic.”