The COVID-19 outbreak has instigated a new paradigm shift on the way we perceive the spaces where we all live and work, shifting the focus towards human health, safety, and well-being. In our previous entries, we have discussed how best practices in building maintenance and building design and operations can help reduce the risks associated to COVID-19. However, at the early stages of the pandemic, it was not really clear which were the main modes of transmission of virus causing COVID-19, especially when considering transmission via airborne droplets. Even now, there seems to be a long-term debate on whether the virus could be transmitted through aerosols or not. However, the possibility of airborne transmission of COVID-19 seems to be more and more convincing every day. In fact, the World Health Organization (WHO) acknowledged airborne transmission as one of the possible modes of transmission for COVID-19 after a group of scientists from more than 30 countries warned the WHO about the accumulated evidence that suggests that the virus can spread through smaller particles that can hang in the air for a significant period of time.
To prevent the spread of COVID-19, already well-known strategies are being implemented by people around the world such as social distancing, wearing a mask, hand-washing and constant disinfection, among others. In outdoor environments, these measures can be effective as virus particles quickly disperse and dilute in the air, reducing the risks of infection. However, indoors, if ventilation is poor, the virus will accumulate in the air, increasing the risk of infection. For this reason, opening windows is a very effective way to reduce the risks of infection. Yet, in some places, when outdoor air conditions are poor or not favourable, opening windows becomes impractical making the building depend entirely on its HVAC (Heating, Ventilation and Air Conditioning) system.
Rethinking Ventilation and Indoor Environmental Quality (IEQ)
Since the WHO has recognized airborne transmission as one of the main modes of transmission, the use of filters of grade MERV 13 or higher has been shown to be effective in removing aerosols that could carry the virus into a confined space, according to William Bahnfleth, chair of the epidemic task force of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).
In fact, the graphs below, which were obtained through our comprehensive cloud-based, real-time and comprehensive integrated building management monitoring service, shows visually exactly how effective high-efficiency filters are compared to regular ones – almost doubling PM2.5 removal compared to outdoors.
Furthermore, research shows a dramatic drop in % transmission rates of viruses when humidity is kept within the human comfort zone (40-60% humidity levels) as shown on the figures below, which makes Indoor Environmental Quality Monitoring (IEQ) a necessary requirement for the spaces we all work and live.
Source: Arundel, Anthony V., Elia M. Sterling, Judith H. Biggin, Theodor D. Sterling. “Indirect Health Effects of Relative Humidity in Indoor Environments.” Environmental Health Perspectives 65 (1986): 351-61
How to Improve IEQ?
Indoor environmental quality (IEQ) refers to the quality of a building’s environment in relation to the health and wellbeing of those who occupy space within it. One of the best ways to improve IEQ and reduce potential risks of viral transmission is through real-time monitoring.
- More control: Real-time monitoring your indoor environmental quality will allow you to realize when there are issues and to take action immediately.
The use of real-time monitors can be used to detect and measure different environmental factors (e.g. CO2, PM2.5, Temperature, Humidity, TVOC etc.) throughout the day, which can give an idea of how risky an enclosed space is in terms of potential viral transmission, among others.
As a first example, improper re-entry cleaning practices can potentially cause accumulation of TVOC which are known to impact human health. In this case, evidence of this behaviour is shown on the figures below where increased re-entry cleaning activities caused significant increases in TVOC concentration inside retail spaces – consumer goods stores (left) and F&B stores (right) – most likely due to the use of inappropriate cleaning materials that contained harmful VOC’s.
In addition, monitoring can facilitate decision-making for building owners and occupants. For example, simple actions such as opening windows can have positive and negative impacts on IEQ. For instance, opening windows is one of the main recommendations to reduce the risks of infection. However, if outdoor conditions are unfavorable, opening windows can present other risks, such as exposure to PM2.5, which has a huge negative effect on human health. With real-time monitoring, building occupants can make more informed health and safety-related decisions. Coupling the practice of increasing fresh air (either naturally by opening windows or via mechanical systems) together with indoor recirculation units that use filters to remove airborne pollutants, can exponentially improve indoor air quality and dramatically reduce the possibility for viral transmission.
Another interesting observation that we can draw from using real-time monitors is the impact that social distancing measures and factory closures over the COVID period have had on atmospheric levels of particulate matter concentration. This has been reported in the news over the past few months and we wanted to see if we could also see these trends in the monitors we have deployed across our projects. Using Hong Kong as an example, we can see a distinct reduction in PM2.5 with an average of over 26 µgm/m3 prior to COVID and an average of 14.6 µgm/m3 during COVID. In the line graphs below the blue line in outdoor PM2.5 levels and the green line is indoor PM2.5 levels. More clearly summarized by-month in the bar graph, we can see that indoor PM2.5 levels have also seen an average reduction, which is an interesting point over overlooked in the news.
In conclusion, by monitoring indoor and outdoor conditions, decisions like turning on the HVAC system or opening windows can be made in a more informed way, protecting building’s occupants and improving building operations.
BEE Monitoring experience
Being a leader in the green building industry, BEE has significant real-time IAQ monitoring consulting experience. With hundreds monitoring projects across the world, we have helped clients achieve their desired levels of health, safety, wellness and comfort by ensuring proper design and operations of their spaces.
