Encyclopedia of Environmental Science and Engineering, Volume I and II

1048 RADON

air, however, the decay products formed are metals which

initially associated with aggregates of water molecules in the

air. These aggregates in turn adhere to airborne dust parti-

cles. When inhaled, the dust particles, if of appropriate size,

will preferentially deposit in the tracheobronchial region of

the lung. Radioactive decay of the short lived alpha emitting

progeny of radon will result in intense local irradiation of

the tissue underlying the deposited dust. It has been calcu-

lated that the vast majority of the total radiation dose to the

lung tissue is due to the alpha decay of Po-218 and Po-214.^12

It is this localized irradiation which is believed to trigger the

development of lung cancer.

In order to have a radon problem in a home, three

conditions are necessary. First, the immediate parent of

radon-222, radium-226, must be present in the underlying

soil or rock to yield a radon source term. Second, the home

must have penetrations in the basement or the ongrade slab

which provide entry points for the gas. Third, the pressure

inside the home must be less than the surroundings so as to

provide a pressure differential to facilitate the entry of radon

into the home. The first condition is geologic in origin and

is met in many locations in the United States. The second

condition is a typical consequence of standard construction

techniques, particularly in homes where a peripheral channel

in the basement slab and an associated sump pump are used

to control wet basement problems. Other points of entry for

radon in a home include unsealed openings around piping,

at or below grade, cracks in the walls and floor, and porous

concrete. The third condition is met by a combination of fac-

tors which include the normal stack effect associated with

the house, combusting fuels for heating, and the use of appli-

ances such as dryers which are vented to the outside. These

conditions are met in homes in much of the northern portion

of New Jersey, and to a lesser extent, in specific locations in

southern New Jersey.

THE NEW JERSEY RADON PROGRAM

Shortly after the Watras incident, Pennsylvania Department

of Environmental Resources personnel contacted their coun-

terparts in the New Jersey Department of Environmental

Protection (DEP) to advise them of the problem. In the

beginning months of 1985, DEP staff working with the New

Jersey Department of Health began to assess New Jersey’s

potential for a radon problem and develop a response to it.

TABLE 1

The Uranium Decay Series

Nuclide Half Life

Alpha

Energy

(MeV)

Beta

Energy

(MeV)

Gamma

Energy

(MeV)

U-238 4.5 × 109 y 4.1−4.2 — —

Th-234 24 d — 0.06−0.2 0.09 (6%)

Pa-234 m 1.2 m — 2.3 —

U-234 2.5 × 105 y 4.7−4.8 — —

Th-230 8.0 × 104 y 4.6–4.7 — —

Ra-226 1600 y 4.6−4.8 — —

Rn-222 3.8 d 5.5 —

Po-218 3.05 m 6.0 — —

Pb-214 26.8m — 0.7–1.0 0.08 (17%)

0.24 (7%)

0.30 (9%)

0.35 (37%)

Bi-214 19.7 m — 0.4−3.3 0.61 (45%)

0.77 (5%)

1.12 (15%)

1.24 (6%)

1.38 (5%)

1.76 (15%)

2.20 (5%)

Po-214 1.5 × 10 −^4 s 7.7 — —

Pb-210 22 y — 0.1 —

Bi-210 5.0 d — 1.2 —

Po-210 138 d 5.3 — —

Pb-210 Stable — — —

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