Feature: Indoor air quality needs addressing to prevent virus spread

Andy Makin, managing director at EnviroVent looks at the issue of poor ventilation in housing and how we may be failing a generation by not addressing it properly.

Back in the 1800s, there was a public outcry about poor sanitation and contaminated water in Britain’s cities giving rise to epidemics, disease and death.

Surveys into sanitation proved that a relationship existed between disease and filth in the environment and it was widely accepted that safeguarding public health was ‘the province of the engineer rather than of the physician’.

As a result, The Public Health Act of 1848 established a General Board of Health to aid local authorities in improving sanitation. Over the next few decades, introducing good sanitation became a priority and as a result, disease and death from associated illnesses, such as dysentery, were reduced and eventually eliminated.

Fast track to 2021 and experts say that current rules on ventilation are failing to stop infections, including Covid-19, being spread amongst the population through shared use of buildings and homes. Evidence shows that Covid-19 is often transmitted through infectious air particles in crowded indoor spaces.

In the journal Science, scientists and engineers point out that while governments have regulations on the safety of food, sanitation and drinking water, there is much less regulation when it comes to pathogens in the air.

Prof Cath Noakes, an environmental engineer at the University of Leeds, said: ‘Air quality is invisible to us so we ignore it, yet it affects us day in, day out, carrying respiratory diseases which affects the probability of people getting infections……spread of infection has not usually been a priority in building design.’

Some experts believe that a revolution is needed in how governments regulate indoor air quality and how the issue is taught to the next generation of ventilation and air conditioning apprentices.

Latest Government guidance on restricting the spread of the virus is that indoor environments should be ventilated as much as possible to reduce the risk of transmission by diluting internal air with fresh outside air. The guidance states that extractor fans with outside vents should be used, or windows should be opened to allow natural ventilation.

Mechanical ventilation has been found to be much more effective than natural ventilation in a recent study by EnviroVent’s parent company S&P UK, entitled The importance of good ventilation (before, during and after a global pandemic): Analysis model of the airborne transmission risk.

The study set out to answer the question of whether natural ventilation – opening windows – is enough to mitigate infection risk from Covid-19 or if a mechanical ventilation system is required. The study looked at three different cases: a classroom, a bar and an office.

It revealed that the Covid transmission risk is reduced by half when using mechanical ventilation compared with opening windows to create natural ventilation.

In addition, the study points out that opening windows as a means of ventilation is not realistic in many cases, as it can cause issues with security and introduce unfiltered, potentially polluted air from outdoors into the home.

The research highlights that natural ventilation may vary significantly from 0 to more than 10 ACH (air changes per hour) under specific conditions. Therefore, mechanical ventilation allows a building owner to set the ventilation rates accurately according to the requirements of British Standards.

Interestingly, in the classroom study, the research showed that mechanical ventilation delivering rates according to the standards managed to eliminate most of the viral concentration during a playground break (30min) and completely removes the infectious particles during the two-hour-long lunch break. By comparison, in a natural ventilation scenario, open windows were not capable of completely removing the concentration of virus during any of the breaks.

The results show the importance of adequate ventilation and reinforce the advantages of mechanical ventilation systems. In particular, mechanical ventilation allows for higher ventilation rates than natural ventilation (in the vast majority of cases), which leads to a lower infection risk.

Although the study covered classrooms and commercial locations, it demonstrates the benefits of mechanical ventilation in reducing and eliminating transmission risks in any situation, compared to natural ventilation.

Through the BEAMA Ventilation group, we are gearing up as an industry to meet the current and future needs of the public who will be tasked with ensuring that their house is sufficiently ventilated to protect occupants from disease and ill health.

While certain members of the public have recognised the health benefits of integrating mechanical ventilation for issues like condensation and mould growth in their homes, which can exacerbate health issues, such as asthma, we need to drive for much greater awareness.

One solution is whole house Positive Input Ventilation (PIV) systems, which can easily be retrofitted into houses or apartments.

They supply fresh filtered air into the home to ventilate the whole property. This method dilutes, displaces and replaces high humidity levels, which not only controls condensation but also improves indoor air quality. PIV is most commonly fitted into renovated and retrofitted properties and good quality, compliant installation is essential.

It is possible to foresee a time in the future when air quality will be as important as ensuring good water quality in a building. In the meantime, it is good practice for the Government to focus their efforts on improving indoor air quality in buildings, to meet the current and future health needs of the public.

Photo by Li Lin