COVID-19 readiness meets airport HVAC systems

Can you really make your airport terminal building pandemic proof? The short answer to this question is “no!” There are too many variables to uncover and consider, such as the various modes of virus transmission — and the infectious dose of SARS-CoV-2, the virus that causes COVID-19, is still unknown. However, as the airline industry recovers from the effects of COVID-19, Hanson highly recommends preparing ourselves, our systems and our terminals and buildings for the next possible epidemic. The first step for heating, ventilating and air conditioning (HVAC) systems is preparing a building readiness plan by reviewing the systems and equipment to mitigate the transmission of pathogens.

According to the Centers for Disease Control and Prevention, “Some infections can be spread by exposure to virus in small droplets and particles that can linger in the air for minutes to hours. … There is evidence that under certain conditions, people with COVID-19 seem to have infected others who were more than 6 feet away. These transmissions occurred within enclosed spaces that had inadequate ventilation.” ASHRAE has held the position that the airborne path was sufficiently likely since early April 2020 and has stated that HVAC systems can decrease risk of airborne or aerosol transmission by reducing the airborne concentration. This is achieved with a combination of increased ventilation and air management, increased filtration efficiency and additional air-cleaning technologies.

Conducting an HVAC risk assessment as a first step toward developing an HVAC systems operational plan[CC1]  will help mitigate virus transmission, monitor systems’ performance and record any adjustments to operate the systems during the pandemic. The analysis includes assessing outside air ventilation and filtration levels, developing an air-cleaning strategy (such as ultraviolet germicidal irradiation), reviewing the systems’ operating hours and assessing the building automation systems’ capabilities. The readiness team also should create work orders to correct issues with the systems and determine if preventative maintenance has been completed. During this process, we document pre-correction, post-correction and post-event operation and then work with our airport customers to develop their overall building readiness plan. Our goal is to help them occupy their buildings as soon as possible and identify mitigating methods to ensure resiliency in the future.

As we complete the risk assessment with our clients, we discuss and identify the various modes of operation (e.g., shutdown, preoccupancy, partial and full occupancy and epidemic or post-epidemic) and work with them to provide safety training for their tenants. As they prepare to reoccupy the building, we recommend that they perform a one-time flush with outside air for at least four hours, then operate the HVAC systems for 24 hours prior to occupancy and review the systems’ trend data. We also recommend that the water systems are flushed, as needed, to avoid contamination and check various water systems for appropriate levels of water treatment. It is also important to verify the supply chain to obtain needed HVAC parts. Finally, we recommend that our clients update their systems manual to have a record of what was done and how the systems should operate.

We hope to never have to worry about another epidemic or pandemic; however, according to the Council on Foreign Relations’ article, Major Epidemics of the Modern Era,” there have been several epidemics and pandemics in the past two decades.

For more information, contact Bill Bradford at or Wade Conlan at