It is estimated that 6,000 to 24,000 people die from lightning strikes each year on the planet 1.
Lightning is the 25th highest cause of death2 in the world.
Nevertheless, the disparities are numerous. Some countries are more affected than others, particularly disadvantaged areas, which are often both the most exposed to storms and do not benefit from the facilities that protect the population3. Although there is no exhaustive census of cases in Europe, a recent study conducted in 20 Western European countries looked at "extraordinary accidents" that have been the subject of media coverage, in an attempt to learn lessons from them.
1) Lightning strikes on people: Who? Where? When?
Our study looked at 215 accidents in which lightning killed 83 people outright and injured 971. Most accidents occur between May and August with a peak in July, which accounts for nearly 30% of annual accidents (followed by August at 22% and June at 18%). Nevertheless, accidents occur throughout the year, including in winter.
Location of the 215 accidents identified in the study
Some general statistics:
- More men are struck by lightning than women (approximately 2⁄3 fatalities)
- Fatal cases are most common in the 40 to 60 age group
- Victims were taking part in leisure activities in nearly 3 out of 5 cases
This “average” statistical profile should not, however, limit the consideration of risk to these characteristics alone. It is important, for example, to highlight the wide disparity in the activities of victims, showing again, if need be, that lightning does not strike hikers and golfers in the vast majority of cases, as is still sometimes believed to be the case.
Where were the victims during the storm?
Our study reveals that victims are, for example, more often struck by lightning at their place of work (nearly 20%) than when hiking in the mountains (13%). There are also the same number of cases of rubbish collectors affected as there are golfers4
What were the victims doing during the storm?
Above all, this type of study confirms the need for increased awareness, particularly regarding the behaviours to adopt and avoid in the event of thunderstorms.
2) What is the real risk of being struck by lightning?
With the exception of astraphobes5 or mystics, the fear of being struck by lightning is not very common. This is in line with the few accidents recorded in our latitudes each year. It is thus tempting to suppose that the probability is infinitesimal when we can estimate that each person will be confronted, throughout their life, with about a thousand thunderstorms. Less than 1% of them will be injured or killed by lightning. This probabilistic vision nevertheless suffers from a dangerous optimism because even if I were to be confronted with 1,000 storms in my life, there would actually be fewer than 100 storms that would generate lightning at less than 500 meters away from me. It is these 100 events that will truly be dangerous; would I be vigilant enough not to underestimate the risk of these 10 percent of truly dangerous cases, and not mistakenly think that they are like the other 90 percent?
>>Learn more: Quel est le niveau de foudroiement de votre commune ?
3) How can the risk be limited?All forms of preventive action are generally divided into 3 phases:
- 1. Before: be aware of a thunderstorm risk before scheduling an activity.
It's an obvious piece of advice, but one that is not always followed, as one of our analyses shows.
By consulting the meteorological status the day before the accidents that took place in France, we can see that in all cases, a warning had been issued. 82% of warnings were "yellow", with this state being associated with locally dangerous phenomena such as thunderstorms, but we must consider whether the general public correctly assess the risk. If in doubt about the weather conditions, change your plans for your activity. If cancelling a tennis training session is not necessarily relevant if you live close to the courts, do not, however, take the risk of continuing with a 3,000-metre climb.
- 02. During : protect yourself
There is only one rule to ensure real safety in the event of a thunderstorm, and that is to take shelter in a "solid" house (ideally equipped with means of protection against lightning!).
This is the famous "When thunder roars, go indoors", a slogan hammered out for nearly 20 years by the NOAA and the NCS, intended to reduce the number of deaths each year on American soil. This is the only recommendation that is unquestionably reliable; the other measures designed to limit the risk in the event of having to stay outdoors do not guarantee an equivalent level of protection... Moreover, you should pay attention to this instruction before you even hear the sound of thunder, but then it would certainly have been more difficult to create such a euphonious slogan! Ideally, safety measures should be taken before you even discern a flash of light in the distance. This is the role of certain systems that guarantee greater efficiency, especially in order to have enough time to take refuge.
- 03. Be careful not to go out too soon
Another result of our study revealed the consequent number of situations where victims were struck when the storm had been present for more than 30 minutes (and often more than an hour), and was spreading slowly (or was even stationary), with often decreasing electrical activity. It is therefore very possible that the victims may have thought that the storm was moving away and had decided to resume their activity prematurely. These cases raise questions about the appropriateness of recommendations (such as "you must wait at least 30 minutes after the last thunder clap to resume an activity") that could be misinterpreted when they are widely used in sports competitions around the world.
Incidents of accidents during a stationary thunderstorm (radar replay)
The (non-) serious consideration of risk in the world of sport will be the subject of a forthcoming article, based on the analysis of recent cases.
2According to the report “Injury facts” publiée par le National Safety Council
3Discover the NGO: ACLEnet which works in Africa to reduce the number of deaths each year.
4Read, for example the report by J.Jensenius of the NOAA
5Astraphobia is the panicked fear of storms
6An evaluation that is certainly schematic but based on an average occurrence of 20 days of thunderstorms per year at one location over a period of 70 years, which is only an average in Europe.
7Further schematic evaluation based on a lightning density of 2 lightning strikes per km2
8The NOAA is the agency responsible for monitoring the atmosphere and oceans in the United States, including the NWS, which is the National Weather Service.
9The number of fatalities is now a half or even a third based on accidents over the last 5 years: rapport Lightning Safety Awareness
10 In particular, Thunderstorm Warning Systems (TWS), which are the subject of an international standard, IEC 63793.