Summer thunderstorms can be exciting, but they also have some
health effects you may not know about.
The summer thunderstorm is great theater. Lightning seems like it
might have been hurled by the hand of an angry god. If it's
close, we're treated to the sharp crack of thunder that makes us
jump and the dog hide. And if it's far away, there's that heavy
kettledrum rumble. The wind whips through. The rain comes in a
frenzy. And when it's all over and the storm has passed, we're
often treated to some of the season's most delectable weather.
Of course all this presumes a view of the proceedings from
somewhere inside. Being outside, with the thunder and lightning,
can be perilous — and very, very wet. But even if you stay
indoors, thunderstorms are associated with some adverse health
effects. The classic example is the arthritis that acts up,
although that may be a psychological phenomenon. Researchers have
documented thunderstorm-related outbreaks of asthma, and there
are hints that storms could cause lung and sleep apnea problems.
So, starting with lightning, the most obvious threat, here are
some of the hazards associated with thunderstorms. You can still
enjoy the show, but may be a little more wary the next time one
Lightning strikes occur because the bottom part of a thundercloud
acquires a negative charge relative to objects on the ground.
Downward "leaders" from the charged clouds carve out columns of
heated, charged particles in the air. These leaders get longer
and longer, till their tips are within 30 to 50 yards of the
ground. When a connection is finally made to the positively
charged ground, or an object on the ground, a huge amount of
current flows out of the cloud — and in a flash — there's a
Lightning strikes are common, occurring 20 million times a year
in the United States. June, July, and August are the peak months,
except in the Southeast and especially Florida, where
thunderstorms and lightning happen year-round. The prime time of
day for lightning strikes is between 3 p.m. and 5 p.m., after the
sun has had a chance to heat up the air and create the updrafts
that form thunderclouds.
One of the many misconceptions about getting hit by lightning is
that it's inevitably fatal. In fact, most people live to tell the
tale. On average, about 60 Americans die each year from lightning
strikes, but four to five times as many survive, although the
injuries can be quite serious.
Another myth is that people burst into flames or, at the very
least, get severely burned by lightning. In truth, there's a
"flashover" effect that keeps much of the current outside the
body. Moisture on the skin may vaporize instantaneously, leaving
behind first- and second-degree burns. Sometimes clothes and
shoes get blown off, so the person is left nearly naked. But the
flashover effect is also a lifesaver and makes deep tissue burns
from lightning a rarity. Cardiac arrest, not burns, is the most
common cause of death from lightning because the electricity
scrambles the electrical system of the heart.
We also tend to have the mistaken idea that the only danger is
from a direct strike. The massive current from a lightning strike
can travel through the ground and, seeking the path of least
resistance, travel through a person standing nearby. People also
get hurt by "splashes" of lightning. Lightning can splash from
one person to another and from a tree to a person. Even when
people are inside, they can suffer splash injuries from indoor
plumbing or telephone wiring that has been electrified by
Survivors of lightning-related injuries may end up with an
assortment of neurological and eye problems. Many victims
experience bad, unrelenting headaches for several months. The
concussive force of lightning can cause the kind of blunt trauma
that people experience when they fall, get hit, or are involved
in a car accident.
The chances of any one of us getting injured by lightning during
our lives is vanishingly small. But if you're outside when a
storm comes through, you want to make a small chance even
smaller. Here are five suggestions from a review article on
lightning injuries written by Drs. Medley O'Keefe Gatewood and
Richard Zane at Harvard and published in 2004 in Emergency
Medicine Clinics of North America.
Seek shelter in a car or bus. If a car
or bus gets hit, the electrical current stays on the outside of
the metal shell of the vehicle. Rubber tires have nothing to do
with the protection.
Seek shelter in a large structure.
Small buildings such as bus shelters or huts on golf courses may
actually increase the risk of lightning injury if they are the
tallest objects in an area. Tents may also be a danger because
the metal poles could act as lightning rods.
Stay away from clearings and single
trees. If you are in the woods, don't head for a
clearing because you'll be the tallest object. Take cover in an
area with small trees or bushes. And if you're in an open area,
don't stand near an isolated tree or group of trees that could
attract a strike. Instead, find a low-lying area and assume the
"lightning position": squatting with feet together and hands over
the ears to protect against acoustic trauma. Gatewood and Zane
said kneeling or sitting cross-legged would also be okay, since
squatting can be uncomfortable.
Don't wait till the clouds are
overhead. Lightning can travel horizontally 10
miles or more in front of the storm clouds producing rain, so a
strike can seem to come, literally, out of the clear blue sky.
One rule of thumb is to seek shelter when the time between seeing
lightning and hearing thunder is 30 seconds or less. Another one
is not to resume outdoor activities until 30 minutes after the
last lightning is seen or thunder heard.
Avoid faucets and landline telephones during a
storm. Plumbing and telephone wires can carry
current from a lightning strike. If you want to be super
cautious, you should turn off electrical appliances and devices
like computers before the brunt of the storm arrives.
Reports of thunderstorm-related asthma go back to 1985 to a
report in The Lancet about a sudden spike in asthma
patients in Birmingham, England, after a July thunderstorm. There
have been reports since from Australia and Canada. Researchers in
Georgia investigated the relationship between the 564
thunderstorms recorded at the Atlanta airport between 1993 and
2004 and over 200,000 asthma-related emergency department visits
at hospitals in the area. They found a real, if modest, 3%
increase in asthma-related visits on days following
The people affected by thunderstorm asthma almost invariably have
seasonal allergies — otherwise known as hay fever — which means
they're prone to having an allergic reaction to pollen, fungal
spores, or both. And the episodes of thunderstorm asthma have
been associated with high pollen and spore counts. So how might
thunderstorms increase pollen and spore counts?
Thunderstorms are created by updrafts of warm, humid air. When
that rising air cools off at the higher altitudes and the
humidity condenses into rainfall or hail, it creates downdrafts
and outflows of cool, dry air that race ahead of the storm and
the rainfall. Most of us have experienced that ominous drop in
temperature and the gusts of wind that signal the approach of a
thunderstorm. According to one theory, those gusts whip pollen
off of grass and trees. Another, more elaborate explanation is
that pollen (and possibly spores also) first gets swept up into
the storm clouds where moisture ruptures the pollen grains into
smaller fragments, which then get transported down to ground
level by cool downdrafts and outflows (see the illustration). The
electrical activity associated with thunderstorms may also play a
role in breaking up the pollen into smaller pieces. This
explanation takes into account the assertion that whole pollen
grains aren't likely to cause asthma because they are too large
to get down into the narrow airways of the lungs. It also
explains why some people claim that they can tell a thunderstorm
is coming by the worsening of their asthma symptoms.
Many people with arthritis are convinced that the condition acts
up and causes more pain when the weather gets bad. For the most
part, research has debunked that belief. Psychologists have
ascribed it to selective matching: an inclination to see and
remember salient coincidences and to ignore contradictory
evidence. In the case of arthritis and bad weather, people may
notice changes in weather when they have more pain because of the
prior belief in a connection, but don't notice when their joints
are feeling fine.
In 2007, Tufts-New England Medical Center researchers reported
findings that go against the grain in two ways. First, they found
a connection between the weather and reports of arthritis pain
among 200 people who had participated in a clinical trial of
glucosamine. Second, knee pain increased not with the falling
barometric pressure that's associated with stormy weather, but
with the rising barometric pressure that usually comes with clear
skies. Their explanation: severe deterioration in weather is
often accompanied by fluctuations in barometric pressure.
A lung collapses when air gets into the space between the lungs
and chest wall and pushes on the lung so it loses its shape. The
medical term for the pocket of air is pneumothorax. Anything that
punctures or tears the lung — a broken rib, for example — can
cause a pneumothorax. But often there's no obvious violation of
the lung. These spontaneous pneumothoraces often occur because
weak spots in the wall of the lung give way, allowing air from
the lungs to escape.
Researchers have documented that hospital cases of spontaneous
pneumothoraces occur in clusters. And it's understood that large
air pressure change outside the body from, say, scuba diving or
airplane travel can trigger a spontaneous pneumothorax. So a
handful of researchers have investigated whether much smaller,
weather-related decreases in air pressure might be associated
with pneumothoraces. If air pressure is low, air trapped inside
the alveoli of the lung might expand and put pressure on the lung
The results of these investigations have been mixed. In 2000,
Dutch researchers found no connection between falling air
pressure and spontaneous pneumothoraces in Amsterdam. Italian
researchers who conducted a similar study in Bologna, Italy, more
recently did. But both groups saw a pattern of thunderstorms
occurring on days just before the clusters of pneumothoraces. One
explanation is that asthma brought on by thunderstorms might
cause pneumothoraces. The humidity and wind of thunderstorms may
also bring about changes in the lungs (mucus retention,
bronchiolar spasm, cough) that add up to make spontaneous
pneumothorax more likely.
People with sleep apnea repeatedly stop breathing for short
periods while they're asleep. Serious cases put a strain on the
cardiovascular system and increase the risk of heart attack and
stroke. In 2010, researchers reported the results of a study of
537 apnea patients at the University of Washington Medicine Sleep
Institute in Seattle. They checked apnea patterns of the patients
while they were in the overnight sleep clinic against barometer
readings during those stays, and found that the number of
obstructive sleep apnea "events" — instances when breathing was
interrupted — increased on the nights when atmospheric pressure
was lower. Thunderstorms weren't part of this study, but falling
atmospheric pressure is a common feature of most storms.
Obstructive sleep apnea is usually caused by soft tissue in the
back of the throat relaxing and blocking the normal flow of air.
Atmospheric pressure may help hold those tissues open a little
bit, so when pressure falls, they relax and interfere with