662 HAZWOPER for General Site Workers III

Ionizing Radiation

Ionizing radiation sources may be found during demolition and construction activities such as tunneling, highway, and road construction. These radiation sources can pose a considerable health risk to affected workers if not properly controlled.

Workers in construction are primarily exposed to natural radiation from the sun, cosmic rays, and naturally-occurring radioactive elements, primarily uranium, thorium, and potassium, and their radioactive decay products, found in the earth's crust. These elements emit alpha particles, beta particles, and gamma rays which are discussed below.

Alpha Particles

Alpha particles are positively charged particles emitted in the radioactive decay of the heaviest radioactive elements.

The primary source of exposure for construction workers is radon, which naturally occurs in rock and soil. Radon can accumulate in crawl spaces, mines, tunnels, basements, and other poorly ventilated areas.

Beta Particles

Beta particles are fast moving electrons emitted from the nucleus during radioactive decay. They travel considerable distances in air but can be reduced or stopped by a layer of clothing, but some beta particles can penetrate the skin causing radiation damage, such as skin burns.

Gamma Rays and X-Rays

Gamma rays are photons that are produced by nuclear explosions, lightning, and radioactive decay. They can pass through several feet of concrete or a few inches of lead. They can also pass through the entire body.

X-rays

X-Rays are high-energy photons produced by the interaction of charged particles with matter, and a few millimeters of lead can stop x-rays. Because of their many uses, x-rays are the single largest source of man-made radiation exposure.

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