If an emergency occurs in which hazardous materials have been released into the atmosphere, you may be instructed to “shelter in place.” This is a precaution intended to keep you safe by staying indoors. It means you should choose a small, interior room, with no or few windows, and take shelter there. It does not mean sealing off your entire home or office building.

Chemical, biological, or radiological contaminants that are released into the environment, accidentally or intentionally, will generate information from local authorities on television and radio instructing you how to protect you and your family.

Because information will most likely be broadcast on television and radio, it is important to keep a TV or radio on, even during the workday.

If authorities advise you to “shelter in place,” it will be important for you to know what to do. The following is advice from the Red Cross.

How to Shelter in Place at Home

• Close and lock all windows and exterior doors.
• If there is danger of explosion, close the window shades, blinds, and/or curtains.
• Turn off all fans and heating and air conditioning systems.
• If you have fireplaces, close the fireplace dampers.
• Make sure you have a working radio.
• Bring your family disaster kit to an interior room without windows that is above ground. An above-ground location is preferable because some chemicals are heavier than air and may seep into basements, even if the windows are closed.
• Keep your pets with you and be sure to have food and water supplies for them.
• It is ideal to have a landline telephone in the room you select. Cellular telephone equipment may be overwhelmed or damaged during an emergency.
• Use duct tape and plastic sheeting (heavier than food wrap) to seal all cracks around the door and any vents into the room.
• Listen to your radio or television until you are told all is safe or you are told to evacuate.

How to Shelter in Place at Work

• Close the business. If customers, clients, or visitors are in the building, ask them to stay. When authorities give instructions to “shelter in place,” they want everyone to do so immediately, where they are, and not drive or walk outdoors.
• Unless there is an imminent threat, ask employees, customers, clients, and visitors to call their emergency contact to let them know where they are and that they are safe.
• Close and lock all windows, exterior doors, and any other openings to the outside.
• If there is danger of explosion, close the window shades, blinds, and/or curtains.
• Have employees familiar with the building’s mechanical systems turn off all fans and heating and air conditioning systems. Systems that exchange inside air with outside air, in particular, need to be turned off, sealed, or disabled.
• Gather available disaster supplies, such as nonperishable food, bottled water, battery-powered radios, first-aid supplies, flashlights, batteries, duct tape, plastic sheeting, and plastic garbage bags.
• Select an interior room above the ground floor with the fewest windows or vents. The room should have adequate space for everyone to be able to sit. Select several rooms if necessary. Large storage closets, utility rooms, pantries, copy, and conference rooms without exterior windows work well. Avoid rooms with mechanical equipment like ventilation blowers or pipes.
• It is ideal to have a landline telephone in the room you select. Cellular telephone equipment may be overwhelmed or damaged during an emergency.
• Use duct tape and plastic sheeting (heavier than food wrap) to seal all cracks around the door and any vents into the room.
• Listen to your radio or television until you are told all is safe or you are told to evacuate.

How to Shelter in Place in Your Vehicle

• If you are unable to get to a home or building quickly and safely, pull over and stop your vehicle in the safest place possible. If it is sunny, try to stop under a bridge or in the shade to avoid being overheated.
• Turn off the engine and close the windows and vents.
• If possible, seal the heating/air-conditioning vents with duct tape.
• Listen to the radio regularly for updated advice and instructions.
• Stay where you are until you are told it is safe to get back on the road. Be aware that some roads may be closed or traffic detoured. Follow the directions of law enforcement officials.

Remember that instructions to “shelter in place” are usually in effect for a few hours only, not days or weeks. There is little danger that the room in which you are taking shelter will run out of oxygen.