Indoor air monitoring: adding another arrow to the quiver

Measuring Indoor Air.

Heating, ventilation, and air conditioning (HVAC) systems are crucial in maintaining indoor air quality in commercial buildings. Until recently, however, little thought has been given to monitoring the presence of airborne microbes that can profoundly impact our wellbeing. 

The COVID-19 pandemic has reminded us of the dangers of viruses, and the potential implications they have on our health, business operations and way of life. During the pandemic, companies were guided by governments as to how to respond to outbreaks of SARS-CoV-2, and how to work together to curb infection rates. This article discusses how the onus has now shifted onto businesses to implement measures to help protect their employees and operations, and how the use of in-air pathogen surveillance can help guide these important decisions.

Data-driven decision making

Governments and public health agencies relied on an abundance of data and predictive models to help develop and execute measures to counteract SARS-CoV-2. This resulted in numerous strategies being implemented across the globe, from lockdowns and mandatory testing to social distancing and remote working. However, as the pandemic transitions into an endemic stage, many government precautions will no longer be enforced. Furthermore, there is a false sense of security stemming from widespread vaccinations, as well as a general desensitisation to the dangers posed by the virus. As public health agencies relinquish their responsibilities for managing SARS-CoV-2, companies must now increase their own diligence, and start investing in tools to help protect their staff and operations. 

Changing tides: addressing the risks of SARS-CoV-2

Infectious diseases have historically come under the realm of public health, making it challenging for the private sector to know how to respond to the ongoing pressures of SARS-CoV-2. Population surveillance through widespread asymptomatic testing was generally accepted during the height of the pandemic, but this method is no longer favoured. Even personal precautions, such as mask wearing and hand sanitising, are being phased out or simply forgotten in daily routines. Although, as staff return to office buildings and workplaces, management still needs to find ways to determine the risk of an outbreak, so that appropriate precautions can be implemented. This can depend on various factors; such as the number of employees, their lifestyles, and the HVAC system or natural airflow in the building, but there are seemingly too many variables to address the risk accordingly. 

Strategic environmental monitoring

Environmental monitoring through the investigation of wastewater offers a potential solution, as it can track the presence of a virus or other pathogens in a specific location. This method has long been used in numerous applications, and is a promising tool for places with semi-permanent residents, such as care homes, children’s homes and prisons. Isolating SARS‑CoV‑2 from effluent can build a picture of viral load in a given area, the information from which could then be used to help businesses develop plans to minimise the spread of disease. But, by the time a spike is identified, it is often too late to implement measures to contain the outbreak. Furthermore, samples often have a plethora of contaminants, including PCR inhibitors, making it challenging to generate actionable results. 

Indoor air monitoring is an alternative environmental monitoring technique being increasingly used, as it can help to detect certain viruses in the air, which is often the route of transmission. SARS-CoV-2, for example, is an airborne virus primarily infecting others via aerosol droplets. Transmission rates have been found to increase with extended close contact with other people and with the accumulation of aerosolised particles, and this effect is compounded by poor ventilation. The common misconception that asymptomatic individuals are less likely to infect others could also increase the danger in these closed indoor settings, as similar viral loads have been identified in individuals regardless of how COVID-19 manifests.

Indoor air monitoring has now been widely tested, including sampling air from HVAC systems in a shared environment, and is proving to be cleaner, easier and safer compared to wastewater monitoring. Sampling air from HVAC systems clearly demonstrated the effectiveness of this method, as it detected SARS-CoV-2 in 75-100 per cent of air samples taken from rooms containing persons with confirmed positive cases. Air sampling is also proven to detect multiple in-air pathogens, such as; influenza A, influenza B, respiratory syncytial virus (RSV) – allowing for a comprehensive environmental surveillance strategy.

Knowing what’s in the air we breathe

In a real-world scenario, collecting samples through HVAC systems may not provide the accuracy needed to make informed decisions. Isolating an outbreak in a multi-story building containing several businesses would be near-impossible, as the further a sample is taken from the source, the less sensitive the test will be. Sampling on each floor, and frequently, could be more beneficial, and yield even greater sensitivity. 

One such in-air pathogen surveillance solution, which has been tested in a variety of settings, including hospitals, schools and retirement communities, is the Thermo Scientific™ AerosolSense™ Sampler. This system is designed specifically for busy indoor environments, and can detect airborne viruses – including SARS-CoV-2, influenza A/B, RSV and many others – in a timely fashion.

Improving ventilation

If a sample returns a positive result, managers can then assess the risk and decide the appropriate course of action. This could be simply to increase short-term personal precautions. For example; temporary mask wearing, reducing the number of staff in the office or improving ventilation in a zone – or more systematic changes, such as upgrading HVAC systems to improve indoor air quality.

Risk management strategies like this are especially important for people with, or living with individuals suffering from comorbidities, as they can be more vulnerable to SARS-CoV-2 and other pathogens. Access to timely information could help these individuals take the required precautions during times of heightened risk. Furthermore, measurements can be taken continuously, making it possible to evaluate the success of different strategies.

Today’s solutions for tomorrow’s challenges

The COVID-19 pandemic has been a stark reminder of the dangers of respiratory viruses to public health, but rarely have we experienced this widespread disruption to our way of life. The worst is seemingly behind us, but SARS-CoV-2 has not vanished, and continues to threaten our health, especially in closed indoor environments. Even when the threat does eventually fade, another airborne virus will undoubtedly arise, providing new challenges to indoor air quality. Luckily, the innovations developed through this critical time will allow us to quickly adapt and respond, offering a potential solution for these future pressures.

Businesses must invest in the appropriate tools to help keep operations running efficiently, and their employees safe, and environmental monitoring through indoor in-air surveillance has been shown to provide the evidence needed to make timely and decisive decisions.

Daniel Mullen is Bio-Aerosol Product Manager at Thermo Fisher Scientific

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