Basic Calculations for Occupational Safety and Environmental Health Professionals - Mathematics and Statistics for the Environment - page 439

15.9.4 a lpha r adiation
Alpha radiation is used for air ionization—elimination of static electricity (polonium-210), clean
room applications, and smoke detectors (americium-241). It is also used in air density measure-
ment, moisture meters, non-destructive testing, and oil well logging. Naturally occurring alpha
particles are also used for physical and chemical properties, including uranium (coloring of ceramic
glaze, shielding) and thorium (high temperature materials). The characteristics of alpha radiation
are listed below.
• Alpha (α) radiation is a particle composed of two protons and neutrons.
• Alpha radiation is not able to penetrate skin.
• Alpha-emitting materials can be harmful to humans if the materials are inhaled, swal-
lowed, or absorbed through open wounds.
• A variety of instruments have been designed to measure alpha radiation. Special training
in use of these instruments is essential for making accurate measurements.
• A civil defense instrument (CDV-700) cannot detect the presence of radioactive materi-
als that produce alpha radiation unless the radioactive materials also produce beta and/or
gamma radiation.
• Instruments cannot detect alpha radiation through even a thin layer of water, blood, dust,
paper, or other material, because alpha radiation is not penetrating.
• Alpha radiation travels a very short distance through air.
• Alpha radiation is not able to penetrate turnout gear, clothing, or a cover on a probe.
Turnout gear and dry clothing can keep alpha emitters off of the skin.
15.9.4.1 Alpha Radiation Detectors
The types of high-sensitivity portable equipment used to evaluate alpha radiation in the workplace
include
• Geiger-Mueller counter
• Scintillators
• Solid-state analysis
• Gas proportional devices
15.9.5 b eta r adiation
Beta radiation is used for thickness measurements for coating operations, radioluminous signs,
tracers for research, and for air ionization (gas chromatograph, nebulizers). The characteristics of
Beta radiation are listed below.
• Beta (β) is a high energy electron particle.
• Beta radiation may travel meters in air and is moderately penetrating.
• Beta radiation can penetrate human skin to the “germinal layer,” where new skin cells are
produced. If beta-emitting contaminants are allowed to remain on the skin for a prolonged
period of time, they may cause skin injury.
• Beta-emitting contaminants may be harmful if deposited internally.
• Most beta emitters can be detected with a survey instrument (such as a CDV-700, provided
the metal probe cover is open). Some beta emitters, however, produce very low energy,
poorly penetrating radiation that may be difficult or impossible to detect. Examples of
these are carbon-14, tritium, and sulfur-35
• Beta radiation cannot be detected with an ionization chamber such as CDV-715.