With relaxation of restrictions and opening of borders and boundaries, an uneasy post-pandemic’ euphoria has emerged. While the business community applaud the initiatives by various governments in relaxing the restrictions, an equal number of people, including families with young children and elderly dependents, remain very concerned, especially with the high number of cases being reported daily.
Coronavirus is being compared to flu-like and many who contracted the Omicron version have stated that it was like “having the flu, but much worse”. Daily case numbers are coming down and hospitalisation statistics show a gradual decline of admissions and resulting fatalities from the virus.
A young girl in her first year at a secondary school contracted Covid last week as a result attending a party in an indoor venue which did not have good ventilation. Six of her friends also contracted the virus.
With no contact tracing, or QR code, the only way they found out was by contacting each other. It took three days due to delays in obtaining PCR test results before she and her family commenced the week-long mandatory isolation. Her father has his own business as a handyman. It is likely he may lose some work to others especially on work that needs to be carried out immediately. Her mother is a project manager looking after campus-style buildings.
With recent rains, she is required to supervise contractors who are addressing leaks and floods in several buildings. This supervision work has now got to be outsourced at an additional cost to the owner. Similar stories appear in social media. Costs therefore are in different forms in living with Covid. Hence the suggestions outlined here for minimising the risk need to be taken seriously
The ethos remains that “cost of consequences will far outweigh the cost of implementing minimisation strategies” – same philosophy that was advocated some 20 years ago in a Climate Change related presentation at a property industry event where there was a slide that showed what the consequences (of not minimising GHG) would be through events such as the 1:500 years flood – now being experienced yearly.
Many questions remain related to long covid and longer-term impact on children and elderly once they have contracted the virus. The economic and social disruptions are being experienced as a result of sporadic shutdowns of childcare centres, educational institutions, aged care centres and nursing homes. Are they being factored into the economic recovery evaluations?
The overall message is that we need to live with Covid. Other than encouragement to getting fully vaccinated there does not appear to be any risk minimisation strategies that need to be followed.
The trend is for each state government or territory to follow each other in relaxing the rules. The current mandate to be removed is of wearing masks indoors. This is of concern since tests carried out, using a breathing manikin and a simulated virus, show clearly that the virus has the potential to stay in the air for extended length of time. How long the virus stays in the air is dependent entirely on the amount of fresh air being introduced into the indoor environment.
The term that needs to be understood is air change rate. In simple terms it is the time taken for air within an indoor space to be entirely replenished by air from outside. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends ventilation rates for schools, offices, shops, restaurants and homes to be from 0.35 – 8 air changes per hour.
While talking about awareness, it is disappointing that there has been so little conversation with respect to ventilation. In recent aged care outbreaks, investigation of existing ventilation did not feature prominently. As covered in previous articles, the airconditioning systems in many aged care buildings use recycled air and rely on openable windows to provide fresh air. Often the windows remain closed for various reasons including security and outdoor prevailing weather. While there were no conversations in the media specifically on ventilation and aged care, it is pleasing to note that the Victorian government has developed detailed guidelines and policies related to Covid and ventilation. They need to be followed diligently.
To remove the requirement of wearing masks without making any reference to ventilation is irresponsible. Once again practical tests show that having maximum fresh air for an indoor environment dilutes virus concentrations. It is like creating an outdoor situation in an indoor setting.
Most high-rise office airconditioning systems have such facilities to inject maximum fresh air. It is acknowledged that employing full fresh air has an impact on energy consumption by having to cool (or heat) the injected fresh air. The answer is that supply air would comprise recycled return air combined with minimum fresh air (to meet code requirements). This could mean recycling a large proportion of the return air. In that case the return air would need to be filtered with good quality filters. As per an explanation provided by Distinguished Professor Lidia Mowrawska, of Queensland University of Technology the virus compositions are:
In simple terms, the finer the filter media the better the chances to arrest the sub-micron virus particles of the sizes shown above.
At the outset of the pandemic, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommended use of air filtration above Minimum Efficiency Rating Value (MERV) -13.
Just as a comparison the High Efficiency Particulate Arrestance (HEPA) filters used in Operating Theatres and Cleanrooms are equivalent to MERV-20+. Once again, the higher the filter efficiency the higher the resistance to airflow requiring the fans to use more energy.
As an alternative or to further improve the safety, consideration needs to be given to dis-infection of the return air using technologies including ultraviolet.
Ultraviolet germicidal irradiation, or UVGI, is the use of ultraviolet (UV) energy to kill viral, bacterial, and fungal organisms. UVGI fixtures produce UV-C energy, which has shorter wavelengths than more penetrating UV-A and UV-B rays and pose less risk to human health. Upper-room UVGI refers to a disinfection zone of UV energy that is located above people in the rooms they occupy or in the air conditioning systems. It kills airborne pathogens in the rooms where it is released.
Hence if these precautionary measures are in place, then removal of mask mandate would be appropriate.
Ultraviolet germicidal irradiation
Image: CDC recommendation
The US Center for Disease Control (CDC) recommends a layered strategy to reduce exposures to SARS-CoV-2, the virus that causes COVID-19. A layered strategy combines multiple prevention strategies such as consistent and correct use of masks, ventilation, physical distancing, cleaning and disinfection, and good hygiene.
Ventilation interventions can help reduce the number of infectious viral particles (for example SARS-CoV-2) in the air.
Ventilation interventions include opening windows, using fans, adding high efficiency particulate air (HEPA) fan/filter systems, and adding upper-room ultraviolet germicidal irradiation (UVGI).
Room air purifiers
For schools, childcare facilities and many domestic applications, the use of air purifiers are becoming more prevalent. However, as stated by professor Lidia Morawska at Queensland University of Technology (QUT), “air purification without ventilation is not a solution”. There is full agreement with this statement.
Location of the air purifiers too play an important role. Tests indicate that the convective plume from our breath rises above our head. This would also be the case for an infected person. Therefore, if the air purifier is situated below head height, then the infected air is drawn down.
Air movement needs to be understood generally as tests also showed that if there were interferences created by fans or air \conditioning outlets then the likelihood of increase of potentially virus laden air at breathing level would rise proportional to the level of interference.
Expertise should be sought from indoor air quality and airconditioning professionals in making spaces utilising mechanically ventilated and airconditioned systems safer.
Cost effective solutions
In German schools, a simple exhaust fan solution is proving to be cost effective. It works by removing “contaminated” air from an indoor environment and replenishing it with fresh air. If there are ceiling fans, they need to be in a mode that pushes air upwards.
Prevention by detection
Carbon dioxide monitoring has become popular. Whilst it provides an indication of ‘lack of ventilation’ it is not an indicator for presence of Sars CoV2 or any other virus. It needs to be used with careful consideration.
Research recently published in The American Journal of Infection Control “represents a breakthrough in the way the virus can be detected before an individual tests positive. “Similar to testing a building’s wastewater, implementing building air sampling on a broader scale could allow for earlier detection of the virus, particularly in shared spaces, ” said a report in the November 2021 edition of Science News
At the same time, a newly developed sensor known as the Scout is being created through a joint project between researchers at RMIT University and Melbourne-based biomedical start-up Soterius.
It aims to quickly and easily detect the virus, even in tiny amounts in the air. The Scout uses a process that mimics the way the virus works in the human body.
“The sensors have specific binding sites on them that are similar to the way the SARS-CoV-2 spike protein binds to our cells, only the virus binds to these sites on the device,” said professor Sharath Sriram from the school of engineering at RMIT University, who leads the program.
A device claiming to detect the virus that causes COVID-19 in ambient air within two to three minutes has been successfully tested at two universities in the US. It was developed by the company Smiths Detection, which says that the test has a sensitivity equivalent to PCR testing. The test is now commercially available at a high cost. Benefits are obvious in spending on prevention rather than on testing after infection.
Governments need to encourage research and development of such sensors – either through grants or through tax deduction incentives.
Measures necessary to live with COVID
Perhaps lessons can be learnt from malaria.
1. Masks and air filtration mirror the mosquito net – especially necessary in potentially virus-infected situations
2. Killing of the virus by disinfectants including UVGI and FAR UVC-222 with the parallel being how mosquito infected areas are being disinfected using chemicals
3. Maintaining good hygiene and proper ventilation under all circumstances (as is done with any other disease)
Needless to say, vaccination remains paramount (as it does with likes of malaria)