In order to maintain a comfortable indoor environment, occupied buildings will feature some form of ventilation and heating / cooling. This may be achieved through natural ventilation (e.g. wind / buoyancy effects), mechanical ventilation (e.g. fans / blowers) or hybrid / mixed-mode (a combination of natural and mechanical) ventilation systems, which due to their differing modes of operation have differing vulnerability to a CBRN attack.
Modern, commercial buildings such as shopping centres, airport terminals and sports venues typically use a distributed (mechanical) heating, ventilation and air-conditioning (HVAC) system. HVAC systems, which can have many points of access, potentially provide a viable, rudimentary means of dispersing chemical or biological agents, and so consideration of measures to reduce this risk may need to be considered:
- Review the design and physical security of your air-handling systems, such as access to intakes and outlets.
- Improve air filters or upgrade your air-handling systems, as necessary.
Additionally, areas which may be considered high risk, e.g. mail rooms, may require dedicated air-handling and filtration. Further advice is available from the Screening Mail and Courier Deliveries page.