Mitigating the risk of SARS-CoV-2 transmission in schools

The COVID-19 pandemic has brought renewed focus on the performance of ventilation systems to minimise the risk of airborne transmission.

SARS-CoV-2 is the virus that causes COVID-19 and transmits when people breathe in air contaminated by droplets containing the virus. While the risk of breathing these in is highest when people are in close proximity, it has become clear in recent times that they can be inhaled over longer distances, particularly indoors.

As such, the suitability and effectiveness of ventilation systems is something many building owners and tenants are reviewing. However, one area under urgent investigation is in education facilities.

GHD has recently undertaken assessments of existing ventilation systems for select schools across Victoria. The review was designed to help each school to understand their ventilation system’s performance and identify areas for improvement, with a specific focus on determining effective ventilation strategies. While the review was prompted by concerns regarding the spread of SARS-CoV-2, the strategies identified typically offer other benefits, such as improvements to indoor air quality, general health, and learning outcomes.

n some schools, current ventilation provisions were found to be not appropriate or insufficient. In addition to recommendations regarding the upgrade of these systems, in many cases other mitigation measures were also recommended, including:

• Control system modifications to increase outside airflow to dilute concentration of airborne pathogens, while minimising associated increase in energy consumption.
• Providing ‘make-up’ air to amenities areas direct from outside instead of from adjacent spaces (for example from nearby offices). This can reduce the chance of SARS-CoV-2 travelling from an infected area to an amenities space, enabling amenities to be used as a ‘safe space’.
• Future proofing ventilation systems. Depending on the outcomes of current research, it may, in time, be proven that high grade air filters are particularly effective in conjunction with other technology at removing SARS-CoV-2 from an air stream. Such filters could be retrofitted to some systems with minimal modifications.
• Using existing ventilation system functionality to purge building air overnight.
• Upgrading air filtration systems to provide much more robust particulate efficiency. Based on current research regarding suspension of airborne pathogens in air, a minimum 60 percent PM1 filter class would reduce the amount of virus in an infected room.