Based on what is known about Radon-222’s primary decay method, why is inhalation so dangerous?

If a quantity diminishes at a pace proportional to its current value, it is said to be subject to exponential decay.

Radon-222 (radon gas) is an alpha emitter.

Its primary decay is as shown below:

\({_{86}^{222}}Rn{ \to _{84}}^{218}Po + \,{\,_2}^4He\)

The alpha rays can be easily stopped by paper or a very thin shielding because they have very low penetration power.

But alpha rays have higher ionization potential than beta and gamma rays. This means that if the radon gas is inhaled, it directly attacks the lungs and other tissues. It is also possible that if a large amount of radon gas is inhaled, DNA cells will be damaged, leading to cancer.

Therefore, inhaling radon-222 is risky because it damages DNA cells, leading to cancer.