the winter months many agricultural workers and commercial
fishermen face an additional occupational hazard - exposure
to the cold. Some health problems can arise including frostbite,
trench foot, and hypothermia. This sheet is designed to provide
readers with basic information on how to prevent cold-related
the body responds to cold.
An individual gains body heat
from food and muscular work, and loses it through convection,
conduction, radiation, and sweating to maintain a constant body
temperature of approximately 98.6°F. The body's first response
to a cold environment is constriction of the blood vessels of
the skin, that reduces heat loss from the surface of the skin
by decreasing peripheral blood flow; and/or shivering, that
generates heat by increasing the body's metabolic rate.
conditions that cause cold-related stresses are low temperature,
cool high winds, dampness, and cold water. Wind chill (temperature
and wind velocity) is an important factor to evaluate when
working outside. For example, when the actual air temperature
of the wind is 40°F and its velocity is 35 mph, the exposed
skin would perceive these conditions as if the equivalent
still air temperature were 11°F. A dangerous situation
of rapid heat loss may arise for any individual exposed to
high winds and cold temperatures.
addition to the cold environment, other major risk factors contributing
to cold-related stresses include:
clothing or wet clothing (the actual effects of cold on
the body depend on how well the skin is insulated from the
use or certain medications may inhibit the body's response
to cold or impair judgment (examples include beta blocks,
neuroleptic drugs, alcohol, and cigarettes);
cold or other disease, such as diabetes, atherosclerosis
and hypothyroidism, may increase risk;
male death rates due to cold exposure are greater than the
rates for females; perhaps because of inherent risk-taking
activities, body fat composition, or other physiological
increases with age;
or immobilization, especially through injury or entrapment.
harmful effects of cold include frostbite, trench foot,
and general hypothermia
occurs when skin tissue actually freezes and cell damage results.
The freezing point of skin is approximately 30°F and windchill
can be a significant factor in accelerating the process. Fingers,
toes, cheeks, nose, and ears are primarily affected. The symptoms
of frostbite include an uncomfortable sensations of coldness;
there may be a tingling, stinging, or aching feeling followed
by numbness. Initially the frostbitten area appears white
and is cold to the touch. This is followed by heat, redness,
and swelling. Occasionally a victim may not be aware of the
damage can be mild and reversible or severe, resulting in
scarring and tissue death. Amputation or loss of function
can be an unfortunate result. First aid includes treating
affected areas with warm water at 102° to 110°F. Be
careful to avoid rubbing frostbitten areas because this can
lead to greater tissue injury. If there is a chance for refreezing,
do not rewarm the affected areas.
foot may be caused by long, continuous exposure to a wet
and cold environment, or actual immersion in water. This may
be a special concern of commercial fishermen. The condition
is characterized by vascular damage. Symptoms include a tingling
and/or itching sensation, pain, and swelling. Blisters may
form and be followed by death of skin tissue and ulceration.
aid treatment for trench foot is similar to the treatment
for frostbite, and includes: moving the victim to a warm area;
treating the affected part with warm water (102°-110°F)
or warm packs; arranging bed rested in a warm environment;
and obtaining medical assistance as soon as possible.
hypothermia is the progressive loss of body heat with
prolonged exposure to cold. Body heat loss is accelerated
more rapidly when a person is wet because of sweat or working
in a damp environment. Most cases of hypothermia develop in
air temperatures between 30° & 50°F, but significant
hypothermia can occur with air temperatures as high as 65°F
(particularly when clothing is wet), or in the water at 72
first symptoms of hypothermia are uncontrollable shivering
and feeling of cold. As the body's temperature continues to
drop, an individual can become confused, careless, and disoriented.
At this point a person may make little or no effort to avoid
further exposure to the cold. For those working around machinery
or animals, accidental injury is an additional risk. When
the core body temperature falls below 86°F, the body's
adaptive mechanisms for reducing heat loss become ineffective
and death can occur.
experiencing mild hypothermia should be immediately moved
to a warm, dry shelter. Further heat loss is minimized by
removing wet clothing and applying warm blankets for insulation.
Warm, nonalcoholic, caffeine-free drinks may be offered. More
severe cases of hypothermia require intensive medical care.
following recommendations may help to reduce the number of cold-related
disorders that agricultural workers experience during the winter
appropriately. Wear at least three layers: an outer layer
to break the wind and allow some ventilation (like gortex
or nylon); a middle layer of wool, down, or synthetic pile
to absorb sweat and retain insulating properties when wet;
and an inner layer of cotton or synthetic weave to allow
ventilation and escape of perspiration (1).
clothing to creates air pockets that help retain body heat.
Layering also makes adapting to changes in weather and level
of physical exertion easier.
available a change of clothing, if work garments become
special attention to protecting feet, hands, head, and face.
Keep the head covered (up to 40 percent of body heat can
be lost when the head is exposed). Fingers and hands lose
their dexterity at temperatures below 59°F.
footgear that protects against cold and dampness. Footgear
should be insulated and fit comfortably when socks are layered.
wearing dirty or greasy clothing because such garments have
poor insulating properties.
hands, face, and feet from frostbite with an on-site source
of heat. Air jets, radiant heaters, or contact warm plates
may be employed.
a heated shelter for workers who experience prolonged exposure
to the equivalent wind-chill temperature of 20°F or
work areas from drafty or windy conditions.
thermal insulating material on the handles of equipment
when temperatures drop below 30F. Do not sit or kneel on
cold unprotected surfaces.
individuals to set their own pace and take extra work breaks
activities, whenever possible, that lead to heavy perspiration.
as many outdoor activities to the inside as feasible, and
when working outside, select the warmest hours of the day.
activities that reduce circulation, such as sitting or standing
in a cold environment for prolonged periods of time.
energy levels up and prevent dehydration by consuming warm,
sweet, caffeine-free, nonalcoholic drinks and soup.
a period of adjustment to the cold before embarking on a
full work schedule.
working alone in very cold weather use a buddy system.
warm shelter immediately following these symptoms: heavy
shivering, an uncomfortable sensation of coldness, severe
fatigue, drowsiness, or euphoria.
workers, or those with certain medical problems, need to
be extra alert about the effects of cold stress. Check with
a doctor about special needs and precautions.
using alcohol or drugs which may impair judgment while working
in a cold environment. Hypothermia commonly occurs in association
with alcohol abuse. In addition to its effects on judgment,
alcohol increases heat loss through vasodilation and may
new workers on the hazards of working in a cold environment.
chapped skin by the frequent application of protective lotions.
in good physical condition.
K A: "Hot and Cold Environments", in Rom W N (ed): Environmental
and Occupational Medicine. 1992. Little Brown and Company,
Safety Council. Pocket Guide to Cold Stress. 1986.
E L: "Temperature Extremes", in Plog B A (ed): Fundamentals
of Industrial Hygiene. 1988. National Safety Council,
"Cold-Related Disorders", in Weeks J L, Levy B S, Wagner
G R (Eds): Preventing Occupational Disease and Injury.
1991. Washington, DC.
H: "Other Physical Hazards and Their Effects", in Levy B
S, Wegman D H (eds): Occupational Health Recognizing
and Preventing Work-Related Disease. 1992. Little Brown
and Company, Boston, MA.
E M: "Illness Due to Thermal Extremes", in Last J M, Wallace
R B: Public Health and Preventive Medicine. 1992.
Appleton and Lange, Norwalk, CT / San Mateo CA.
Publication #: FS677
is apart of
a series from the Rutgers Cooperative Extension, Rutgers, the
State University of New Jersey. Publication date: February 1993.
Zhao, Project Director of Agricultural safety and Health Program,
in consultation with Ann L. Kersting, Rutgers, The State University
of New Jersey, New Brunswick, NJ 08903.
Disclaimer and Reproduction Information: Information in
NASD does not represent NIOSH policy. Information included in
NASD appears by permission of the author and/or copyright holder.