Basic Calculations for Occupational Safety and Environmental Health Professionals - Mathematics and Statistics for the Environment - page 436

Low Temperature + Wind Speed + Wetness = Injuries and Illness (15.21)

The ACGIH recommends protective clothing for temperatures less than 41°F (5°C). To estimate the
amount of clothing insulation required (in clo units), the following formula is used:

I clo = 11.5(33 - T db )/ M (15.22)

where
I clo = Insulation (clo units, where 1 clo = 0.155 K⋅m 2 /W).
T db = Dry bulb temperature (°C).
M = Metabolic rate (watts).

The major injuries associated with extremes of cold can be classified as being either generalized
or localized. A generalized injury from extremes of cold is hypothermia. Localized injuries include
frostbite, frostnip, and trenchfoot.

• Hypothermia results when the body is unable to produce enough heat to replace the heat
loss to the environment. It may occur at air temperatures up to 65°F. The body uses its
defense mechanisms to help maintain its core temperature.
• Frostbite is an irreversible condition in which the skin freezes, causing ice crystals to
form between cells. The toes, fingers, nose, ears, and cheeks, are the most common sites
of freezing cold injury.
• Frostnip is less severe than frostbite. It causes the skin to turn white and typically occurs
on the face and other exposed parts of the body. There is not tissue damage; however, if
the exposed area is not either covered or removed from exposure to the cold, frostnip can
become frostbite.
• Trenchfoot is caused by continuous exposure to cold water. It may occur in wet, cold envi-
ronments or through actual immersion in water

15.9 RADIATION

15.9.1 d eFinitions
Absorbed dose is the energy imparted by ionizing radiation per unit mass of irradiated mate-
rial. The units of absorbed dose are the rad and the gray (Gy).
Activity is the rate of disintegration (transformation) or decay of radioactive material. The
units of activity are the curie (Ci) and the becquerel (Bq).
Alpha particle is a strongly ionizing particle emitted from the nucleus of an atom during radio-
active decay, containing two protons and neutrons and having a double positive charge.
Alternate authorized user serves in the absence of the authorized user and can assume any
duties as assigned.
Authorized user is an employee who is approved by the radiation safety officer and radiation
safety committee and is ultimately responsible for the safety of those who use radioiso-
topes under his/her supervision.
Beta particle is an ionizing charge particle emitted from the nucleus of an atom during radio-
active decay, equal in mass and charge to an electron.
Bioassay means the determination of kinds, quantities or concentrations, and, in some cases,
the locations of radioactive material in the human body, whether by direct measurement
(in vivo counting) or by analysis and evaluation of materials excreted or removed from the
hu ma n body.
Biological half-life is the length of time required for one-half of a radioactive substance to be
biologically eliminated from the body.