Can you survive being struck by lightning?

The image of lightning as automatically fatal is wrong: survival is the normal outcome, at roughly 90 per cent, and the United States averages around twenty deaths a year against hundreds of injuries. The reason is flashover — most of the current travels over the wet surface of the body rather than through it, and the whole event lasts on the order of tens of microseconds, so relatively little charge passes through tissue. What kills is cardiac arrest at the moment of the strike, which is why immediate CPR matters so much and why lightning casualties carry no residual charge and are safe to touch. Survivors frequently report long-term effects that have nothing to do with burns: memory problems, chronic pain, sleep disturbance, tinnitus and personality changes. Roughly a third of strikes happen indoors or in vehicles through conducted current in plumbing, wiring and telephone lines rather than by direct hit.

What changes the figure

• Immediate CPR is the intervention that changes outcomes; casualties hold no charge
• An enclosed vehicle or substantial building is protective; an open shelter or tree is not
• The frequently cited odds of being struck in a year are on the order of one in a million in the US

Around 90 per cent of people struck survive. The common belief that a strike is automatically fatal is not supported by the statistics.

Physiology, not instruction. Every figure here is a population range under particular conditions, and individual variation is large — temperature, exertion, fitness and health move all of them substantially. Nothing on this page is medical advice.

Conditions

• How long can you survive in freezing water? Around an hour before unconsciousness in water near 0 °C — but the first minute is the one that kills most people.
• What happens to your body in a vacuum? You do not explode. Consciousness goes in about fifteen seconds from oxygen leaving the blood.
• How long can you survive in extreme heat? It depends on humidity more than temperature — once the wet-bulb temperature reaches about 35 °C, sweating cannot cool you at all.
• How long can you survive in extreme cold? Hours in still air with dry clothing; under an hour in wind at -30 °C — and people have survived core temperatures near 12 °C.
• How much radiation can a human survive? Below about 1 sievert most people recover; around 4.5 sieverts kills roughly half; above 8 sieverts survival is very rare.
• How long can you survive carbon monoxide exposure? Hours at low concentrations, minutes at high ones — and it has no smell, colour or taste to warn you.
• How long can you survive in a house fire? Around three minutes in a modern room before flashover, and smoke rather than flame is what kills most people.
• How loud does a sound have to be to kill you? Sound alone cannot exceed about 194 dB in air — beyond that it is a blast wave, and blast is what causes injury.
• How deep can a human go before pressure kills them? About 200 metres on a single breath, around 60-70 metres on air, and roughly 500-700 metres in a saturation chamber.
• How much g-force can a human survive? About 4-6 g sustained before blacking out, 9 g in a pressure suit, and over 100 g briefly in a crash.
• How much electricity can a human survive? Current decides it, not voltage — around 100 milliamps through the chest can stop the heart.
• How long can you survive in boiling water? No meaningful time. Water at 100 °C causes full-thickness burns instantly, and burns over a large area are fatal.
• How long can you survive at high altitude? Indefinitely up to about 5,500 metres if you acclimatise. Above 8,000 metres the body only deteriorates.
• How long can you survive if an aircraft cabin decompresses? Roughly 30 to 60 seconds of useful consciousness at 35,000 feet — which is why the mask goes on before helping anyone else.