Effects of Lightning
To be injured or temporarily disabled one may not essentially be
struck by lightning. Even if one is close to the point of strike he may
receive lethal injuries to which the victim may succumb.
Lightning may injure or kill human beings and animals, basically in
five primary ways:
1. Direct strikes: The entire lightning current may pass
through or over the body as a result of the lightning being attracted by
the body. Example: A person in an open field may be the subject of a
direct lightning strike.
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Lightning may injure or kill human beings and animals. |
2. Side flashes: The entire lightning current or a part of the
lightning current may pass through or over the human body due to the
transfer of flash from a lightning struck object to a body in the
proximity. Example: A person underneath a large tree or inside a tent on
wooden poles may be subjected to a side flash if the tree or the tent is
struck.
3. Step potential: A partial current may pass through the body
if two parts of the body in contact with ground align in the direction
of the potential gradient developed due to the injection of current into
earth from a nearby lightning strike. Example: The two feet of a person
separated in the direction of increasing potential.
4. Touch potential: A partial current may pass through the body
if part of a body comes in contact with a higher elevation of the
lightning struck object while the other part remains in contact with
ground. Example: A person touching a flag pole by hand while standing on
ground. Accidents due to touch potential may also arise when a person is
using line connected telephones, repairing electrical systems connected
to the power line or in contact with any metallic part which is exposed
to the path of lightning current (e.g. metallic railing from the roof
top which is connected to the lightning protection system at the roof
top level)
5. Proximity to the strike: The shock wave generated by the
lightning current due to the sudden expansion of air may damage the skin
or ear drums when a person is very close to the point of strike.
There are several secondary effects, such as falling from higher
elevations due to the momentary shock, falling of heavy materials from
structures (detached due to lightning strike) on the person, burns due
to volatile materials in the surrounding catching fire, psychological
trauma etc.
The passage of current inside the body may lead the person into
ventricular fibrillation (unsynchronized muscle operation of the heart),
respiratory arrest (inability to breath), burning of vital organs such
as brain, liver, kidneys etc. and internal bleeding due to bursting of
blood vessels. The person may also suffer from system damage, broken
bones and loss of hearing or eyesight. Lightning injuries can lead to
permanent disabilities or death. On an average, 20% of strike victims
die and 70% of survivors suffer long term disabilities.
These injuries are primarily neurological, with a wide range of
symptoms, and are sometimes difficult to cure.
A person struck by lightning does not carry any current or charge,
hence he should be attended immediately and given first aid.
Almost 90 percent of the lightning related deaths due to primary
causes could have been avoided if the deceased had been attended within
a short time period.
The vast majority of lightning casualties can be easily, quickly and
cheaply avoided if the proper measures are followed.
Hence, the general public needs increased awareness of the lightning
hazards and knowledge of lightning safety including procedures of
essential first aid i.e. Cardio Pulmonary Resuscitation (CPR) or at
least mouth-to-mouth resuscitation.
The lightning current flowing along the tree due to a direct strike
may jump into the people around the tree and flow into earth as the
resistance of the human (or animal) body is much less than that of a
tree. This is termed a side flash. Courtesy: Handbook on Lightning
Safety by Dr. Chandima Gomes |
