Ventilation systems may assist in the control of the incident environment. Crews should be aware of the type, location, and operation of the control systems.
At incidents involving fire or hazardous materials, ventilation systems should not be turned off or reconfigured until a risk assessment has been made and the full consequences of these actions to the public, firefighters and any fire development are known.
The design and topography of the infrastructure should be considered, including:
- The position of any ventilation outlets, where the products of the incident may affect those on the surface or remote from the incident
- The direction of any mechanical forced ventilation so that safe areas for members of the public and operational bridgeheads can be established
- Any 'piston' effect or other uncontrolled air movement
In most circumstances emergency ventilation and evacuation procedures will be implemented before the arrival of the fire and rescue service, or other responders, either automatically or by the infrastructure manager
The positioning of air inlets outside the infrastructure should be identified to ensure that exhaust gases are not entering the ventilation system. Incident commanders should also consider the effect that the incident may have on the occupants, wider community and environment, such as the effects of any ventilation system exhaust carrying contaminates into the community.
If reasonably practicable the infrastructure manager should be advised of the intended tactical plan. It must be made clear that there should be no changes to any automatic ventilation or fire control systems settings, for the duration of the incident or until the incident commander requests such a change.