Ms Orla Hegarty:

I am grateful for the opportunity to attend this session. I am an architect and academic at the UCD school of architecture, planning and environmental policy. My expertise is the science of prevention because although the virus is biological, the pandemic, which spreads from one person to another, is highly environmental. Buildings are key to suppressing the pandemic. Prevention is about managing people and managing air. Vaccines alone cannot end this. They need the support of a parallel prevention plan.

Looking at buildings in Ireland, we see the following. More than half of the people who died were infected in just 0.03% of buildings. Over half of the cases in workplace outbreaks have been in just 150 buildings. Infection in overcrowded private homes is twice the rate of uncrowded homes. One in four school buildings has had a Covid-19 index case in the past four months.

The problem is infected air. We now understand that risk of transmission is predominantly indoors and very specific to certain buildings and indoor air conditions. These conditions are preventable, and this knowledge is key to stopping infections and to opening buildings at low risk. Most transmission is not from hands touching surfaces, it is from inhaling infected air. Masks are the only protection at close range. Outdoors, the virus is diluted and blown away. However, in buildings and vehicles, it can build up, fill a space, linger for hours and infect many people. Viral particles in the air behave a little like smoke and must be cleared out.

Many countries are achieving low-risk social and economic activity using prevention policies that manage people and their air. These strategies include the following: providing public health information; reducing occupancy, that is, the number of people; limiting certain activities; setting indoor air standards; measuring unsafe, stale air; improving ventilation and filtration; and, sometimes, doing structural or engineering works to buildings.

Indoor air can be measured and managed. This week, international researchers said “preventing respiratory infection, like reducing waterborne or food-borne disease, is a tractable problem”. Indoor spread is measurable and controllable. They warn that. “For decades, the focus of architects and building engineers was on thermal comfort ... initial investment cost, energy use, and ... performance ... [and] infection control was neglected.” This was not always the case. Ireland regulated overcrowding in bedrooms to prevent TB. Before the modern era of energy efficiency and airtightness, architecture and public health were very closely aligned and that is why ventilation is regulated. However, the balance has shifted away from disease prevention as the current regulations aim only to “provide adequate ventilation while limiting energy use and avoiding occupant discomfort”. One hundred years ago, Chicago suppressed the 1918 pandemic with targeted measures, including building inspectors who signed off on ventilation as a condition of trading. The city of Chicago reopened within six weeks. There was no second wave and no vaccine.

With regard to the focus on what is high risk, international evidence points very clearly to which buildings and activities are high risk and where to target resources. There is a significant body of research from theoretical and experimental sciences and building case studies. Super-spread events, where many people are infected at once, indicate the particular environmental conditions of spread. This means that targeted suppression can be very effective, as seen in Japan and other places.

There is a need to target the clusters. Covid-19 has very particular characteristics. Most people do not spread the virus to anyone else. It is said to be “highly over-dispersed”, meaning spread is not a factor of average contacts. Suppressing the pandemic, therefore, is less about rules for people and more about rules for places. This is an opportunity to target interventions because most infected individuals do not contribute to the expansion of an epidemic, so the effective reproduction number could be drastically reduced by preventing relatively rare super-spread events. These super-spread conditions can arise in any enclosed space with two people or many. Indoor risk is about the building, its management and operation, the number of people and the activity. There are strong seasonal factors because indoor air quality changes with the weather, the season and the operation of the building. Infection risk indoors can be reduced by 50% with increased airflow, and by almost 90% with airflow, filtration and wearing masks. Although data in Ireland are limited, the patterns of Covid spread are very similar to other countries, so public health measures can be targeted to have the most impact.

I will now look at the high-risk areas. With regard to vehicles, high levels of ventilation and filtration are critically important in cars, vans, buses and aircraft. An outbreak on an aircraft into Dublin last summer resulted in 13 cases on the aeroplane and 59 cases in total, across six HSE regions.

With regard to housing, infection rates are double in overcrowded private homes, according to the CSO data. A significant number of infections happen within households, and rates are higher in households with children. Inadequate space in institutional and shared housing is high risk, such as in dormitories, hostels and emergency homeless accommodation. Direct provision centres have had 82 outbreaks with an average of ten cases each. Traveller and Roma housing have had 423 outbreaks with an average of 12 cases.

With regard to schools and childcare, more than one in four schools has had a Covid index case since February and, in total, there have been almost 2,500 cases linked to 579 outbreaks in schools. Last week alone, there were 61 outbreaks in schools, which was 20% of all outbreaks. Of 633 cases linked to outbreaks last week, more than one third, or 36%, were in schools and childcare facilities. There have been almost 2,000 close contact cases in childcare and after-school facilities since last July and 342 outbreaks in approximately 900 childcare buildings, that is, more than one third of childcare facilities have had an outbreak.

In hospitals, nursing homes and residential care, 55% of the people who died from Covid-19 in Ireland, were infected in fewer than 0.03% of all buildings. A mere 667 buildings accounted for the infections that led to more than half of the deaths. There have been 600 outbreaks in 581 nursing homes, but it is very uneven. In Kildare, 87% of all nursing home deaths were in just a quarter of the buildings and that needs further investigation. Inadequate ventilation is linked to poor respiratory health in older people.

More than half of all infections in workplace outbreaks were in meat and food plants. There were nearly 3,500 cases in outbreaks with an average of more than 40 cases per building in those. There have been 96 outbreaks in construction. One meat plant alone had an outbreak with 226 cases. One construction site outbreak had 148 cases.

I will deal with indoor dining, bars, gyms, places of assembly. Some places have significantly higher risks, particularly where people are indoors in close proximity for long periods of time and without masks, such as in restaurants, pubs, theatres, cinemas, hotels, and entertainment and sports venues. An outbreak in a café in Cork resulted in 57 cases. At an extreme level, one breach in hotel quarantine in Australia directly resulted in 18,000 infections, 800 deaths and a 112-day lockdown. Breaches in buildings can have a very significant impact.

Certain activities have higher risks, including exercise in gyms and for sports, singing in choirs and at religious events, and shouting, because they generate aerosols and involve deep breathing. A recent outbreak in a gym in Canada resulted in 480 cases and it spread to 49 workplaces.

This knowledge provides an opportunity for more sure-footed policies. Eliminating unsafe conditions protects everyone, including children, people with compromised immunity and those not vaccinated. It also mitigates the risk of variants, and of super-spread events. Vaccines alone cannot provide enough headroom for reopening. A prevention plan is needed.

Safe indoor air has many measurable benefits for health and well-being. It mitigates all respiratory illness, including flu, and future-proofs for another pandemic. Aside from all these benefits, good indoor air quality is a legal requirement of workplace health and safety.

This understanding of transmission and prevention has significant implications, and indicates a need for fundamental review of some incorrect assumptions in public health policy; public health information; reopening plans; sectoral rules; tracking and tracing procedures; epidemiological modelling; and building standards, inspection and enforcement. To ensure that policy is consistent and scientifically up to date, an active multidisciplinary approach is needed. It needs collaboration and engagement across disciplines including biomedical, epidemiological, environmental, sociological and other sciences.

Further analysis of these patterns of spread and investigation of buildings is needed. There must be a risk-based approach to target interventions and effectively use limited resources. If this virus were in water or food, the response would be to take samples, investigate the source and eliminate the problem. So it must be with infected air.

This is a third way that steers a scientific course between lockdown and uncontrolled spread. However, it requires a paradigm shift so that public health policy is evidence based and responsive to new knowledge. There needs to be a shift in perception that we cannot afford the cost of control, because the economic costs of infections can be enormous and may well exceed costs of containment.