Polonium is a rare, radioactive element that occurs naturally in the environment, but it’s also found in tobacco smoke. When people smoke cigarettes for many years, polonium-210—a particularly dangerous isotope—builds up in their lungs. This buildup happens because tobacco plants absorb polonium from the soil and fertilizers, and when the leaves are burned, the smoke carries tiny particles of polonium into the smoker’s lungs.
To understand how much polonium might accumulate over 30 years of smoking, we need to look at how much is present in each cigarette and how often someone smokes. On average, a single cigarette contains a very small amount of polonium-210—about 0.01 to 0.1 picocuries (a picocurie is one trillionth of a curie). That might not sound like much, but because polonium-210 is extremely radioactive and emits alpha particles—which are especially damaging to living tissue—even these tiny amounts can be harmful over time.
Let’s do some simple math: If someone smokes one pack (20 cigarettes) per day for 30 years, that’s about 219,000 cigarettes. If each cigarette delivers around 0.05 picocuries of polonium-210 (a middle estimate), then over three decades this person would inhale roughly 11 million picocuries (or about 11 microcuries) of polonium-210 directly into their lungs.
But here’s where it gets complicated: Not all inhaled polonium stays in the lungs forever. Some is exhaled or coughed out; some dissolves into bodily fluids and gets distributed throughout the body; some is excreted through urine or feces; and some decays radioactively inside the body before it can be eliminated naturally (polonium-210 has a half-life of about four-and-a-half months). The actual amount retained depends on many factors: how deeply you inhale smoke; your lung health; your metabolism; even your diet.
Still, studies have shown that smokers have significantly higher levels of radioactivity from polonium-210 in their lungs compared to non-smokers—sometimes several times higher after decades of smoking. The radioactivity isn’t spread evenly throughout the body either: Because alpha particles don’t travel far through tissue but deliver intense energy right where they stop
