DR.TSUBOKURA'S RADIATION LECTURE VOL.154

Author: Masaharu Tsubokura M.D., PhD.

Editor: Yudai Kaneda

307 Radioactive radon is found in the atmosphere.

December 5, 2020

We are surrounded by a variety of natural radioactive substances, from which we are exposed to a certain amount of radiation on a daily basis.

We have introduced potassium-40, which is found in certain amounts in our bodies; tritium (hydrogen-3), which occurs naturally and is produced within nuclear power plants; and polonium-210, which is found in seafood. These radioactive substances primarily enter our bodies through eating and drinking.

Another substance that needs to be introduced is radioactive radon. Radioactive radon is produced when the radioactive substance radium—you may have heard that it occurs in hot springs and in soil—is transformed and drifts in the atmosphere as a gas.

As radioactive radon constantly spreads through the atmosphere from the ground and buildings, we breathe it into our lungs on a daily basis. The radioactive radon that is taken in by the body is altered further, moving around as another radioactive substance and emitting radiation in other parts of the body.

Because the density of radioactive radon varies from place to place, it is difficult to comment generally; however, internal exposure caused by inhaling radioactive substances from the air accounts for approximately 20% to 30% of the daily radiation we receive from the surrounding environment.

308 Japanese houses have lower radioactive radon levels.

December 12, 2020

We are surrounded by a variety of natural radioactive substances, from which we are exposed to a certain amount of daily radiation.

One example is radioactive radon. Radioactive radon is produced when radium, which is found in the soil and in buildings, changes and spreads through the atmosphere. In our daily lives, we routinely inhale radioactive radon from the atmosphere, resulting in internal exposure.

The density of radioactive radon varies depending on the location. It is diffused outdoors when it comes out of the ground, but it accumulates indoors. In places where the density is high, it is necessary to control radon by ventilating and sealing the floors and walls. Furthermore, radon levels increase in places that are close to the ground, such as basements and caves.

On average, in areas, such as Europe, where people live in stone houses, indoor radon density is greater resulting in higher exposure. On the other hand, Japanese houses tend to have better ventilation, resulting in lower exposure. The indoor radon levels in Japan are less than half of the global average, but the average levels in some Northern European and South American countries are two to three times higher than the global average.