Sheltering in place is required when a hazard is outdoors and the conditions are unsafe for citizens without the proper protective equipment. You may be advised to shelter in place for tornadoes, human-caused threats, or chemical spills or biological / radiological hazards. If and when an announcement to shelter in place is given, you should do the following:
For natural hazards, seek shelter in an interior room with no windows or in the basement with a solid enclosure above and around you.
For hazards that are chemical, radiological, or biological in nature outside of your home or office, we are less concerned with structural integrity, but rather how very small particles can enter it.
In these cases you should stay indoors. Don’t go outside for any reason. Close all open doors and windows. Turn off your furnace, air conditioner, or ventilation system and find a room or area without windows and outside vents. Depending on the type of incident occurring outside, you may need to seal doors and windows with plastic and tape.