Immediate danger? Call 911.
A radiation alert may involve a transport/industrial incident, a dirty bomb, a nuclear detonation or a facility event. San Onofre's reactors permanently ceased operation in 2013 and the site is decommissioning; do not mistake an old power-plant chapter for a current local evacuation plan. [R07]
If you are near a nuclear blast when it occurs, turn away, close and cover your eyes, drop face down and remain down until the heat and shock waves pass. Then reach shelter promptly. A dirty bomb uses ordinary explosives to scatter radioactive material; it does not produce a nuclear explosion. Do not touch debris, and seek an undamaged building away from the immediate blast danger. [R08, R09]
If a radiation release occurs and you have no contrary official direction, get inside a substantial building promptly. A basement or central interior area, away from exterior walls and roof, offers better protection. A car is poor shelter. If your building is burning, structurally unsafe or the location of the release itself, move to a safer nearby shelter and obtain emergency help. [R01, R02, R10]
Close windows and doors and, if readily possible, turn off equipment that draws outside air inside. Do not delay shelter to tape windows, retrieve supplies or drive across town. Listen for instructions. Plan to remain sheltered for at least 24 hours unless officials tell you otherwise or an immediate life-threatening danger requires moving. Reaching 24 hours is not an all-clear. [R01, R02]
Carefully remove the outer layer of clothing without shaking dust loose; bag it and keep it away from people and pets. Get inside before spending time washing. Gently wash exposed skin and hair with soap/shampoo and water, without scrubbing or scalding. Do not use hair conditioner. Keep cuts covered; put on clean clothing. If no shower is available, wash exposed areas at a sink or use damp cloths. This removes radioactive material; it cannot undo an exposure already received. [R03, R06]
A face covering may reduce inhalation of dust while you reach shelter. It does not shield your body from penetrating radiation. Dense building materials provide shielding; plastic sheeting does not. [R01, R06]
Use sealed or protected food and drinks. Wipe the outside of containers before opening them. Follow official drinking-water restrictions: boiling does not remove radioactive materials. Tap water can still be used for washing/decontamination under CDC guidance. Do not assume washing exposed outdoor produce makes it safe. Continue prescribed medicines that were protected indoors; wipe exposed containers as instructed. [R04]
Potassium iodide, or KI, protects only the thyroid against radioactive iodine. It does not protect the rest of the body or against other radioactive materials. Take it only when public-health/emergency officials or your clinician direct you; correct timing and individual risk matter. It never replaces sheltering or evacuation. Do not leave shelter to search for it or use iodine supplements or table salt as substitutes. [R05]
Send one short status message to your family contact: who is with you, where you are sheltering, and any urgent need. Do not go outside to collect relatives already sheltering at a school or care facility. Bring pets inside; if they were outside, follow CDC's washing and indoor-waste guidance. Seek urgent help for severe injury and follow the announced route and destination if told to evacuate. [R02, P04]
Prepare now: choose the best available shelter area at home and at places you regularly visit, and keep a radio, light, charging power, medicines and simple washing supplies accessible. Practice getting everyone there without using an elevator or leaving anyone dependent on help unassigned. This is a planning exercise, not a prediction of a local radiation event.
https://www.cdc.gov/radiation-emergencies/response/get-inside.html
https://www.cdc.gov/radiation-emergencies/treatment/potassium-iodide.html