The term "sheltering in place" means to get inside a building and remain there during a chemical emergency rather than evacuate the area. Though the natural tendency is to flee from a vapor cloud, it actually may be more dangerous if you have to go through toxic vapors or if you can't outrun them. Sheltering in place is usually advised when there has been a serious hazardous chemical spill that has quickly caused a toxic atmosphere, and there is not enough time to safely evacuate. Usually, the toxic vapors are dispersed by the wind before an area could be completely evacuated. Sheltering in place is not likely to last more than an hour or two.
If there is a chemical release in your area, you will probably be notified by the emergency alert system. There will be a banner on the bottom of your television, a notice on your radio, and/or the outdoor warning sirens will sound. On the other hand, there may be a time when you are closer to an accident. At those times, be calm and trust your senses. If you hear a strange sound like an explosion; if you see a strange cloud; if you smell a strange odor; if you feel nauseous or have burning or tearing eyes; act immediately--don't wait for the sirens. If it is obvious that you can safely evacuate the area, leave but don't take any chances. Sheltering in a building is better than sheltering in a car.
Where do I shelter in place?
If you are told to shelter in place or if you believe you need to, you should immediately go inside any building close by. If you are not by your own house, a church, school, or store are good options. If you are not near any buildings, even your car is a better choice than staying outside. If there is a building nearby, gather your family and pets and go inside immediately. If your children are at school or daycare, do not try to get them. The staff at those facilities should be trained to shelter in place. It is also possible the school or daycare may be out of harm's way. Your home is the best place to shelter because you are more likely to know where things are that will help you shelter better.