Shelter-in-place is a method of self-protection from airborne contaminants. In the case of a release of toxic airborne material, shelter-in-place can be more effective than an evacuation.
Shelter-in-place
Close all doors, including internal doors, and lock all windows. Windows seal better when locked
Seal any gaps around windows and doors with tape or wet towels. The bottom of doors are especially prone to leak. Close curtains and drapes
Extinguish any open flame such as Bunsen burners and gas stoves
Window air conditioners should be turned off, inlets switched to closed position, and vents sealed with tape and plastic sheeting, wax paper, or aluminum wrap, if possible
Chemical fume hoods should be turned off after experiments are terminated, then sashes should be lowered and sealed shut
Turn off all exhaust fans such as bathroom and kitchen fans, then seal fan openings
Do not use elevators as they can act as pistons pulling air in from the outside
Do not use the telephone except for emergency purposes to avoid overloading the phone system
If the fumes begin to bother you, breathing through a damp cloth or handkerchief can many times offer some relief
When the situation is over, open all doors and windows and place ventilation on 100 percent fresh air to remove any contaminants that have built up inside the building
This is not an alternative to evacuating a building when the alarm sounds, shelter-in-place only when directed to do so by authorities.