How long can a family stay in a sealed room?
The Federal Emergency Management Agency recommends that individuals allow ten square feet of floor space per person in order to provide sufficient air to prevent carbon dioxide build up for up to 5 hours. Many chemical releases would be diluted within a few hours, so the direction to shelter-in-place would likely be made for a short time period while a chemical cloud dissipates. The need for long-term sheltering-in-place, e.g. having a three-day supply of food and water, is important for families preparing for emergencies when local authorities would tell them to stay put rather than evacuating.
