Fact check: What's the best thing to do if nuclear war starts

1. Summary of the results

Based on the analyses provided, there is consistent expert guidance on immediate actions to take in the event of a nuclear detonation. The International Commission on Radiological Protection provides the most authoritative advice: go inside and stay inside, particularly in the center of a building or basement to minimize radiation exposure ^[1].

The US government through FEMA reinforces this guidance, emphasizing getting inside a sturdy building and staying inside for at least 24 hours while staying tuned for further instructions ^[2]. Additional survival protocols include removing contaminated clothing and following instructions from authorities ^[1].

Key survival principles identified across sources include:

• Safe distance from the nuclear explosion
• Shielding from radiation
• Time decay - allowing radioactive materials to decay over the critical first 72 hours ^[3]
• Advanced preparation through emergency kits and identifying nearby fallout shelters ^[2]

2. Missing context/alternative viewpoints

The original question lacks crucial context about current geopolitical tensions that make this question particularly relevant. Recent events include US military strikes on Iranian nuclear sites as of June 22, 2025, with the UN Security Council holding emergency meetings ^[4]. The UK has updated contingency plans to prepare for possible direct military attacks by Russia, including nuclear attack scenarios ^[5].

Risk assessment perspectives are notably absent from the immediate survival guidance. One analysis emphasizes the importance of evaluating nuclear war risk and understanding various scenarios in which nuclear conflict could occur ^[6]. This suggests that preparation involves both immediate response protocols and longer-term risk evaluation.

The analyses reveal a gap between individual survival advice and systemic consequences. While sources focus on personal protection, one analysis indicates that a nuclear attack on America's missile silos could result in 90% of Americans facing severe consequences including acute radiation poisoning and widespread radioactive fallout ^[7].

3. Potential misinformation/bias in the original statement

The original question itself does not contain misinformation, but it oversimplifies a complex scenario. The phrasing "if nuclear war starts" suggests a binary event, when nuclear conflicts can range from limited tactical strikes to full-scale strategic exchanges with vastly different survival requirements.

The question may inadvertently promote fatalistic thinking by focusing solely on post-detonation survival rather than prevention and de-escalation efforts. The UN Secretary-General's recent call for "a return to diplomacy and a peaceful solution" ^[4] suggests that diplomatic solutions remain viable even during heightened tensions.

Government and emergency management agencies benefit from promoting preparedness messaging, as it demonstrates competency and can reduce panic during actual emergencies. However, the consistent messaging across multiple authoritative sources (International Commission on Radiological Protection, FEMA, scientific publications) suggests the advice is based on genuine protective measures rather than political positioning.