Time-weighted average (TWA)The average
concentration of a contaminant in air during a
specific period, usually an 8-hour workday or a
Threshold limit value (TLV)An atmospheric
exposure level under which nearly all workers
can work without harmful effects. TLVs are
established by the American Conference of
Governmental Industrial Hygienists (ACGIH).
NAVOSH PROGRAMS THAT ADDRESS
We will now discuss the administration of various
NAVOSH programs that address specific hazards.
These hazards include hearing conservation, sight
conservation, respiratory protection, heat stress,
electrical safety (tag-out program), and personal
protective equipment. In addition, we will cover
hazardous material control and management, asbestos
control, gas free engineering, and lead control.
OPNAVINST 5100.23C, chapters 7 through 27, and
OPNAVINST 5100.19B, volume I, part B, chapters B1
through B12, discuss these subjects in detail. The basic
criteria are similar, whether applied ashore or afloat.
Refer to the appropriate NAVOSH manual for program
HEAT STRESS CONTROL AND
We define heat stress as any combination of work,
air flow, humidity, air temperature, thermal radiation, or
internal body condition that strains the body. Heat stress
becomes excessive when the strain to regulate its
temperature exceeds the bodys capability to adjust.
Personnel affected by heat stress can suffer fatigue,
nausea, severe headache, and poor physical and mental
performance. As body temperature continues to rise
(because of prolonged exposure), heat rash and heat
injuries (such as heat cramps, heat exhaustion, and heat
stroke) occur. Heat stroke severely impairs the bodys
temperature-regulating ability and can be fatal.
Recognizing heat stress symptoms and getting prompt
medical attention for affected persons are all-hands
From 1989 to 1992, 68 people received injuries
from heat exhaustion or heat stress at shore activities.
All of these injuries involved lost time away from work.
Thirteen people lost 5 or more workdays. Of the 41
incidents involving military people, 29 (71 percent)
people were drilling, playing, or taking part in physical
fitness training. The rest were working.
Aboard ship, nearly 50 heat stress reports were filed
in 1991, most involving personnel wearing the
fire-fighting ensemble (FFE). During Operation Desert
Storm, the control of heat stress among engineering
plant watch standers was critical. In the hot climate
around Saudi Arabia, ships were unable to maintain air
conditioning and ice machines that broke down from
overuse. Heat stress caused by air and water
temperatures above 90°F threatened operational
Symptoms of Heat Stress
The following arc the symptoms of heat stress and
the steps you should take to help the victim:
Heat Exhaustion: Victims have pale and clammy
skin and experience profuse sweating. Their pulse
is fast but weak, and their breathing is fast and
shallow. They may experience weakness, nausea,
dizziness, and mild cramps. Move victims to a cool
location and seek medical attention for them as soon
Heat Stroke: Victims have hot, flushed, dry skin.
Their pulse is fast and strong, and their breathing is
fast and deep. They may twitch or vomit. Shock will
follow. Heat stroke is a life-threatening medical
emergency. Call a medical emergency immediately.
Controlling Heat Stress
You can encounter heat stress aboard U.S. Navy
ships in workshops, laundries, sculleries, engineering
spaces, food preparation spaces, and steam catapult
spaces. Detailed surveys of ship spaces have confirmed
that these heat stress conditions often have been so
severe that a limit was placed on personnel exposures to
avoid serious harm. The primary correctable causes of
heat stress in these spaces were as follows:.
Excessive steam and water leaks
Boiler air casing leaks
Missing, damaged, improperly installed or
deteriorated thermal insulation on steam piping,
valves, and machinery
Ventilation system deficiencies, including design
deficiencies, missing or damaged duct work,
misdirected terminals, improper or clogged
screens, closed or partially closed CIRCLE
WILLIAM dampers, dirty ventilation ducting,
and inoperative fan motors and controllers