Lightning injury: risks, first aid and what happens afterwards

RoSPA says lightning strikes the ground in Britain about 300,000 times a year, and that 30 to 60 people are struck each year, with on average 3 of them (5 to 10%) dying. It points out that UK mortality statistics showed two deaths from lightning in 2005. These are small numbers, which is one reason people underestimate the risk.

RoSPA says those most at risk are people who spend time outdoors in unsheltered places, such as golfers, hill walkers, swimmers, construction workers, rock climbers, fishers, boaters, campers, outdoor DIYers and agricultural workers. About 80% of victims are male, which RoSPA relates to the higher number of men in outdoor work and leisure. Research has also shown that proximity to water increases the risk.

RoSPA describes three routes. In a direct strike lightning hits the person and goes to earth through them. In a side flash it hits another object and jumps sideways to hit the person. In a ground strike it hits the ground and travels through it, hitting the person on the way. Understanding this explains why standing near, not only under, tall objects or in open water is risky.

RoSPA adds that the most dangerous time is when the likelihood of being hit is underestimated, for example before the storm or when you think it is over, and that people are predominantly hit before and after the peak of a storm.

RoSPA suggests checking the weather forecast before setting off, and thinking about a less exposed activity if storms are forecast. For a storm already under way, it describes the flash-to-bang method: count the seconds between the lightning flash and the thunder, and divide by 3 to estimate the distance in kilometres. If the gap shrinks, the storm is approaching.

The 30/30 rule is to seek shelter if flash-to-bang is 30 seconds or less, and to stay in shelter until 30 minutes after the last thunder, because lightning can travel up to 10 miles and trailing clouds can catch people by surprise.

• Shelter in a large building or a motor vehicle; RoSPA says the inside of a car is a safe place because lightning spreads over the metal before earthing through the tyres.

• Avoid wide open spaces, exposed hilltops and open beaches, and get off the water to the shore quickly.

• Do not shelter beneath tall or isolated trees; RoSPA says it has been estimated that one in four people struck by lightning are sheltering under trees.

• If there is nowhere to shelter, make yourself as small a target as possible by crouching with feet together, hands on knees and head tucked in.

• Put aside unnecessary metal objects such as golf clubs, and be aware of umbrellas, bicycles, wire fencing and rails.

• Indoors, RoSPA says lightning can be conducted through aerials, pipes or other wires, and advises not using the telephone except in an emergency until the storm is over.

RoSPA says to call the emergency services, because the casualty will need help as soon as possible, and to apply first aid if you know it. The casualty does not carry a charge: you will not receive an electric shock. A lightning strike is not usually instantly fatal, but the heart or breathing may stop, so prompt cardiopulmonary resuscitation (CPR) is likely to save the person's life.

General electric shock first aid from NHS inform and St John Ambulance sets out the same logic for any electrical injury: assess the area, call 999 (or 112), and check airway, breathing and circulation. NHS inform says the current may stun the person as it passes through the body, which can stop breathing and heartbeat (cardiac arrest), and can cause burns where it enters and leaves the body. St John Ambulance lists a burn and cardiac arrest as signs that someone suffering an electric shock may have, and says to treat any injuries after a primary survey.

NHS inform advises not to move a person with an electrical injury unless they are in immediate danger. During a continuing storm, that judgement may include the risk of further strikes, so rescuers should also think about their own shelter.

NHS inform says an electrical burn may be very small or not visible at all, but can still cause damage deep in the body's tissues. That is why someone who has been struck and seems to have recovered still needs to be seen by healthcare professionals, who can check heart rhythm and look for burns and other injuries.

The pages read for this guide do not give a list of long-term effects of lightning injury or figures for recovery, so this page does not either. Emergency departments assess people after electrical injuries, and anyone with ongoing symptoms after a strike should tell the clinicians who see them that lightning was the cause.

RoSPA notes that workplaces have a duty to ensure the health, safety and welfare of staff under the Health and Safety at Work Act 1974, and that outdoor work in exposed places should be reflected in the risk assessment. For events it recommends monitoring local weather from the day before, having a method of warning and evacuating people at risk, defining safe structures and locations, setting criteria for suspending and resuming activity, for example the 30/30 rule, and making sure participants, officials, spectators and staff know the dangers.

Anyone struck by lightning should be assessed by an emergency department or ambulance service, and these are NHS services in the UK. Follow-up, for example for burns or heart rhythm checks, is arranged by the hospital team or GP. Private clinics are not part of emergency response; if symptoms such as palpitations or burns appear later, the GP or NHS 111 is the usual route.