A recent tragedy in my state serves as a reminder
of the dangers of lightning. A teenager was hit by a ‘bolt from the blue’
during his first week of work on a vegetable farm. The owners have asked me to
spread the word about lightning safety, in the hope that something positive can
come from this terrible occurrence.
The challenge to farmers is that agricultural work
must be done during a variety of weather conditions. Farm work doesn’t stop
just because the weather forecast calls for rain or thunderstorms. The key to
keeping your family, employees, visitors
(and yourself!) safe is knowing when to interrupt or cancel farm activities and
having a plan to protect people from injury or death when thunderstorms
There are millions of lightning strikes every
year, and though the odds of getting hit are low, they are high enough that the
risk must be taken seriously. Lightning is more deadly than hurricanes or
tornadoes, killing an average of 73 people and injuring 300 others annually in
the United States.
The National Oceanic and Atmospheric
Administration (NOAA), home to the National Weather Service, provides a lot of following
information about the nature of lightning and how to avoid its perils. Some of
the following is adapted from their web site http://www.lightningsafety.noaa.gov/.
Lightning is a gigantic electrostatic discharge--the
same kind of electricity that can shock you when you touch a doorknob--between
a cloud and the ground, other clouds, or within a cloud. It is caused by the
attraction between positive and negative charges in the atmosphere, resulting in
the buildup and release of electrical energy. This is associated with rapid
heating and cooling of the air which produces a shock wave that creates
Thunder is the sound made by a flash of lightning.
As lightning passes through the air, it heats the air quickly, causing it to
expand rapidly and create a sound wave. That sound, thunder, travels about a
mile every 5 seconds. If you count the seconds between the flash of lightning
and the crack of thunder and divide by 5, you get the number of miles away from
you, so 10 seconds is 2 miles. Normally, you can hear thunder about 10 miles
from a lightning strike. Since lightning can strike outward 10 miles from a
thunderstorm, if you hear thunder, you are likely within striking distance of
While many lightning casualties happen at the
beginning of an approaching storm, more than half of all lightning deaths occur
after a thunderstorm has passed. The lightning threat diminishes after the last
sound of thunder, but may persist for more than 30 minutes. When thunderstorms
are in the area, but not overhead, a lightning threat can exist even when skies
are clear. If you can see lightning or hear thunder, the risk is present.
Louder or more frequent thunder means lightning activity is approaching,
increasing the risk. Coordinators of outdoor events, including farmers and
their crew leaders, should monitor the weather and know when to evacuate workers
to safety, erring on the side of caution.
There is no safe place outside when thunderstorms
are in the area! If you hear thunder, you are likely within striking distance
of the storm. Adhere to the slogan: When Thunder Roars, Go Indoors! Too many
people wait far too long to get to a safe place when thunderstorms approach.
Unfortunately, these delayed actions lead to many of the lightning deaths and
injuries in the U.S.
Some safety organizations promote the “30-30
rule.” If the time delay between seeing the flash of lightning and hearing the
bang of thunder is less than 30 seconds, you should already be moving toward
shelter. To be safe, outdoor activities should cease a half hour before and
after a thunderstorm, since lightning can strike 30 minutes before or after a
Have a lightning safety policy for your farm, and
make sure all employees understand it. This should include: canceling or
postponing outdoor activities early if thunderstorms are expected; making sure that
crew leaders or other supervisors know they must stop work if the weather
becomes threatening; making sure crew leaders pay attention to early signs of
thunderstorms such as high winds or dark clouds and do not start any new task
that cannot be stopped quickly; making sure that crew leaders can communicate
quickly with all workers, regardless of their location on the farm, using radio
or other devices; making sure that everyone working outside or in unsafe
structures such as greenhouses has the ability to get to a safe place quickly. Everyone
on your farm should know the procedure for contacting emergency services if
cell phones are not available, or lack reception.
Relatively safe places during a thunderstorm are substantial
buildings and fully-enclosed, metal-topped vehicles. A substantial building is
one that is fully enclosed with a roof, walls and floor, and has plumbing or
wiring that provides grounding. Once inside, stay away from showers, sinks,
bath tubs, and electronic equipment such as stoves, radios, corded telephones
and computers. Unsafe buildings include car ports, open garages, picnic
shelters, pavilions, tents of any kinds, sheds and greenhouses.
Fully enclosed metal-topped vehicles include cars,
vans, buses, trucks, or tractors with an enclosed cab. Unsafe vehicles include
golf carts, convertibles, or any open cab vehicle. While inside a safe vehicle,
do not use electronic devices such as radio communications during a
thunderstorm, and keep windows closed. If you drive into a thunderstorm, slow
down and use extra caution. If possible, pull off the road into a safe area. Do
not exit the vehicle during a thunderstorm.
If someone is struck by lightning, get immediate
medical attention. Lightning victims do not carry an electrical charge and are
safe to touch. Call 911 and monitor the victim. They may need CPR or an
automated external defibrillator; is your farm prepared to provide either of