University of California, Berkeley
igh temperatures and the rush
of summer activity increase
risks of heat-related problems.
Heat can cause plenty of harm
short of fatality, and not only in warmweather
seasons. It is a fact of life in
vineyards across the nation.
In California, grape growers and
workers face legal as well as physical
heat-related challenges. A state regulation
designed to reduce the risks of heat
illness in outdoorworkplaces took effect
inmid-summer 2006, adding to employers’
responsibilities for safe operation.
The rule obligates all covered
employers, including vineyard operators,
to take specific measures to help
workers control heat stress and get
timely care for heat-related illness. (See
Basics section, page 90). It carries significant
penalties for noncompliance.
During the 2009 mid-May heat
wave, the California Division of Occupational
Safety and Health (Cal/
OSHA) shut down eight farm labor
contractors in the central and southern
valleys for violations of the heat illness
prevention regulation. Charges included
not providing adequate drinking
water or shade for employees
working in very high temperatures.
Cal/OSHA can stop operations with
an Order to Prohibit Use (OPU) when it
finds workers exposed to an imminent
hazard, until it is satisfied that the
employer is ready to safeguard them.
The first three OPUs in heat-related cases
were issued in 2008.
Regardless of legal mandates, it
pays to help workers minimize heat
stress impacts. But following rules,
keeping the Igloos® full, having shade
nearby, and reciting a litany of
advice to drink lots of water, beware of stress
symptoms, and rest when necessary
goes only so far.
How heat hurts
Humans can perform work under a
wide range of conditions as long as
their internal organs and biochemical
reactions are doing well, which
depends on their temperature being
within a narrow range around 98.6ºF.
When bodies get too cool or warm, natural
processes that add or release heat
kick in to restore the norm.
Although “feeling hot” causes discomfort
and distraction, the cooling process
often gives rise to greater dangers.While
heat stress tends to be more of a problem
when the weather is hot, high ambient
temperature is not its primary cause.
Heat from solar radiation and surrounding
air can affect vineyard workers
butmost of the heat that they have to cope
with is producedwithin their own bodies.
The body’s metabolism generates some
heat even at rest.When it speeds up during
physicalwork, its yieldof heat as a byproduct
This heat raises internal temperature,
threatens normal functioning, and triggers
dissipation mechanisms. Internally
generated heat is more difficult to release
where the air is hot, humid, or still. Both
retained heat and the body’s attempts to
shed it can eventually cause symptoms
recognized as a “heat illness” that impairs
physical or mental activity, reduces performance,
increases risk of accidents, and
endangers life. Heat stroke, themost serious
such illness, is amedical emergency.
Although less critical ailments —
heat exhaustion, heat syncope (fainting),
heat cramps, and heat rash — are
not immediately life-threatening, they
reduce well-being and performance
and can progress to heat stroke if not
treated. The sidebar describes common
symptoms of and treatment guidelines
for these illnesses.
Even minor effects of excess body
heat and the loss of fluid through
sweating may cause damage.
Subtle discomfort, weakness, blurred
vision, slowed reactions, diverted attention,
lapses in concentration or judgment,
reduced coordination, and irritability
add to chances of workers
hurting themselves and also translate
into higher production costs. Heat stress
is probably under-credited as a factor
contributing to workplace accidents.
HEAT RASH – Acute skin inflammation and
clogging of sweat ducts. Regarded as the
least severe of heat illnesses. Though it usually
causes only temporary discomfort, it can
lead to a bacterial infection that shuts down
the function of sweat glands. Rx: Cleanse the
affected area thoroughly and dry completely.
A mild steroid cream, calamine, or other
soothing lotion may help relieve discomfort
HEAT SYNCOPE – Loss of consciousness,
generally sudden, due to lack of sufficient
blood and oxygen to the brain. Greatest
danger is secondary injury from a slip or
fall. Most likely to affect people not yet
acclimatized to work in hot environments.
Heat stress can cause syncope by
diverting blood to extremities or lower
body at the expense of the brain. Rx: Rest,
ventilate, and drink plenty of water or
HEAT CRAMPS – Painful, involuntary muscle
contractions – most common in calves,
thighs, arms, and abdomen -- heavy
sweating, and thirst. Often extremely
uncomfortable and can be completely
disabling. Typically occur during or after
hard work and are induced by electrolyte
deficiencies that result from extended
of intense sweating. Rx: Rest and
drink plenty of water or electrolyte fluids.
HEAT EXHAUSTION – Symptoms include
fatigue, headache, dizziness, muscle
weakness, nausea, and chills, tingling of
hands or feet, confusion, loss of coordination,
fainting, and collapse. Occurs during
exertion and results from dehydration,
lack of acclimatization, reduction of blood
in circulation, strain on circulatory system,
and reduced flow of blood to the brain.
Rx: Rest in the shade or a cool place.
Drink plenty of water (preferred) or electrolyte
HEAT STROKE – The most extreme consequence
of uncontrolled heat stress, a medical
emergency that can develop suddenly
from an untreated condition of heat exhaustion.
Skin is hot and dry, body is typically
hotter than 104°F and no longer able to cool
itself, and themind is confused, delirious, or
convulsive. Brain damage and death may
result. Rx: Summon aid. Immediately move
to the coolest place available, loosen clothing,
fan and douse or spray the body continuously
with a cool liquid. Begin to
replenish body fluids by drinking. Get medical
attention and/or transport to a medical
facility as soon as possible.