One of the instructions you may be given in an emergency where hazardous materials may have been released into the atmosphere is to Shelter-in-Place. This is a precaution aimed to keep you safe while remaining indoors. This is not the same thing as going to a shelter in case of a storm. Shelter-in-Place means selecting a small, interior room, with no or few windows, and taking refuge there. It does not mean sealing off your entire home or office building.
Chemical, biological, or radiological contaminants may be released accidentally or intentionally into the environment. Should this occur, information will be provided by local authorities on television and radio stations on how to protect you and your family. Because information will most likely be provided on television and radio, it is important to keep a TV or radio on, even during the workday. The important thing is for you to follow the instructions of local authorities and know what to do if they advise you to Shelter-in-Place.
Local officials on the scene are the best source of information for your particular situation. Following their instructions during and after emergencies regarding sheltering, food, water, and cleanup methods is your safest choice.
Remember that instructions to Shelter-in-Place are usually provided for duration of a few hours, not days or weeks. There is little danger that the room in which you are taking shelter will run out of oxygen and you will suffocate.