Sheltering in place means staying inside a building and sealing it off from an outside threat, whether that’s a chemical spill, a severe storm, a radiological event, or an active danger nearby. The specific steps depend on the type of emergency, but the core idea is the same: get indoors, reduce your exposure, and stay informed until authorities give the all-clear.
What Sheltering in Place Actually Involves
Unlike evacuation, sheltering in place keeps you where you are. You’re turning your home, office, or school into a protective barrier between you and whatever is happening outside. In a chemical or radiological event, that means preventing contaminated air from getting in. In a tornado, it means getting to the most structurally protected part of the building. In an active threat, it means locking down and staying hidden.
A formal shelter-in-place warning (designated SPW in the Emergency Alert System) signals a significant, confirmed threat where the onset time is short. You may hear it through your phone’s emergency alerts, local radio, TV broadcasts, or outdoor sirens. When it comes, you need to act quickly, not prepare from scratch. That’s why the supply and planning steps below matter before anything happens.
Supplies to Keep Ready
The baseline recommendation is at least one gallon of water per person per day, with a minimum three-day supply on hand. For a household of four, that’s 12 gallons just for drinking and basic hygiene. Store water in a cool, dark place and rotate it every six months.
For food, stock non-perishable items that don’t require cooking or refrigeration: canned goods with pull-tab lids, peanut butter, crackers, dried fruit, and granola bars. A manual can opener is essential if any of your cans lack pull tabs. Keep a three-day supply at minimum, though a two-week supply gives you a much larger margin if utilities fail or roads close.
Beyond food and water, a basic shelter kit should include:
- Battery-powered or hand-crank radio for receiving emergency broadcasts when power is out
- Flashlights and extra batteries
- First aid kit with basic medications (pain relievers, antihistamines, any prescriptions you take daily)
- Plastic sheeting and duct tape for sealing windows and vents
- Charged portable battery pack for your phone
Sealing a Room Against Contaminated Air
If the emergency involves a chemical release, industrial accident, or radiological material, your goal is to stop outside air from entering the building. OSHA recommends turning off all fans, heating systems, air conditioning, and clothes dryers immediately. Pay special attention to HVAC systems that automatically exchange indoor and outdoor air, as these actively pull contaminated air inside if left running.
Choose one interior room, ideally with few or no windows and above ground level (chemical vapors that are heavier than air tend to settle low). Close and tape off every vent in that room. Use plastic sheeting secured with duct tape over windows, doors, and any gaps. Pre-cut sheets to fit your chosen room’s openings so you’re not measuring and cutting during an emergency. Wet towels rolled against the base of doors add an extra layer of protection against airborne particles.
This kind of seal is temporary. A well-sealed room will eventually run low on fresh oxygen if you stay too long, so this approach is designed for hours, not days. Listen to your emergency radio for the all-clear signal before opening up.
Radiological Events: Time, Distance, and Shielding
Radiation exposure follows three principles that directly shape how you shelter. First, time: the less time you spend exposed, the lower your dose. Getting indoors quickly matters enormously. Second, distance: radiation intensity drops with the square of the distance, meaning doubling your distance from the source cuts your exposure to one quarter, not one half. Moving to an interior room puts more walls between you and any fallout outside. Third, shielding: dense materials like concrete, brick, and earth block radiation far more effectively than wood or drywall. A basement with concrete walls is the strongest shelter most homes offer.
If you’re caught outside during a radiological event, get inside the nearest solid building as fast as possible. Remove your outer clothing before entering (this alone can eliminate a large percentage of surface contamination), bag it, and shower if water is available. Stay in the most interior, lowest part of the building until you receive official guidance.
Sheltering During an Active Threat
An active shooter or violent threat requires a fundamentally different response than an environmental emergency. The widely taught framework is run, hide, fight, in that order of priority.
If you can safely escape the building, do it immediately. Leave your belongings. Help others get out if you can do so without putting yourself at risk, and warn anyone heading toward the danger. Call 911 once you’re in a safe location.
If escape isn’t possible, sheltering becomes about concealment and barricading. Lock the door. If it doesn’t lock, barricade it with heavy furniture. Move away from the door and out of any sightlines. Stay low, stay quiet, and silence your phone completely, not just the ringer but vibration as well. Don’t open the door for anyone until law enforcement identifies themselves and you can confirm the threat has ended.
Pets and Animals
Your pets need their own supplies. The CDC recommends a two-week supply of food for each animal, stored in waterproof containers, along with a two-week water supply. Keep non-spill food and water dishes in your kit. For cats, include a portable litter box and enough litter. For any pet, pack plastic bags, paper towels, and disinfectant for cleaning up accidents in a confined space.
During the emergency itself, keep pets in the sealed room with you. Animals can become anxious in unusual situations, so having a carrier or leash accessible helps you maintain control. If you need to shelter in a sealed room for air quality reasons, your pets are breathing the same air and need the same protection.
Sanitation When Utilities Fail
If water service or plumbing stops working, you need an alternative for human waste. A medium-sized plastic bucket with a tight-fitting lid works as an improvised toilet. Line it with heavy-duty garbage bags, and after each use, add a small amount of cat litter, sawdust, or disinfectant to control odor and absorb moisture. Tie off and replace the bag as needed, and store sealed waste bags away from your living and food areas.
Keep a supply of one-gallon zip-close bags for storing clean items separately from waste, and pack hand sanitizer or disinfecting wipes for hygiene when water isn’t available for handwashing. These details feel minor until you’re 48 hours into a shelter situation with no running water.
Staying Informed While Sheltering
Your battery-powered or hand-crank radio is your lifeline. Tune to your local NOAA Weather Radio frequency or a local AM/FM news station. Emergency broadcasts will tell you when conditions have changed, when the threat has passed, and when it’s safe to leave. After an initial warning, authorities typically issue follow-up statements with updated information about the hazard’s scope and expected duration.
Resist the urge to step outside to check conditions yourself, especially during chemical or radiological events where the danger is invisible. If your phone still has service, text rather than call. Text messages use less network bandwidth and are more likely to get through when cell towers are overloaded. Save your phone battery for receiving emergency alerts rather than scrolling social media for updates that may be unreliable.
Preparing Your Space Before an Emergency
The best time to figure out your shelter plan is right now. Walk through your home or workplace and identify the room you’d seal off: interior, minimal windows, close to water and a bathroom if possible. Measure the windows and door in that room so you can pre-cut plastic sheeting. Store your supplies in or near that room.
If you live in an apartment building, know where the building’s mechanical systems are controlled and whether management has a shelter-in-place protocol. In an office, identify who on staff is familiar with the HVAC system and can shut it down quickly. Practice the basics with your household so everyone knows which room to go to, where the supplies are, and how to seal the space without needing instructions.