Outdoor Release

For a release into a building air intake, shut off the supply from that intake, but otherwise follow the advice for an indoor release; in particular, evacuate the building.

For an open-air outdoor release, do the following:

• Shut off HVAC fans.
• Close fresh air intake dampers.
• Close exhaust dampers: with the HVAC off, they can act as intakes.
• Turn off exhaust fans in bathrooms, utility rooms, kitchens, etc.; these are commonly controlled separately from the HVAC system.
• Close windows and doors.
• People should stay indoors, unless authorities give an evacuation order.
• People should retreat to a safe zone in the interior of the building.