Smoking indoors adds a measurable amount of ionizing radiation exposure annually, primarily due to the presence of radioactive substances like polonium-210 in tobacco smoke. Estimates of the additional radiation dose from smoking indoors vary widely but can be significant, ranging from tens to over a hundred millisieverts (mSv) per year depending on smoking intensity and environment.
The main radioactive contributor in tobacco smoke is polonium-210, a naturally occurring alpha-emitter that accumulates in tobacco leaves from the soil and fertilizers. When tobacco is burned and inhaled, polonium-210 deposits in the lungs, delivering localized alpha radiation doses that contribute to lung cancer risk. Heavy smokers can receive an effective radiation dose from polonium-210 in the range of about 100 microsieverts (µSv) up to 160 millisieverts (mSv) annually, with some estimates leaning toward the higher end for heavy indoor smokers. This dose is comparable to or even exceeds the radiation exposure from some nuclear accidents or high natural background radiation areas.
To put this into perspective, the average natural background radiation dose worldwide is about 2 to 3 mSv per year from cosmic rays, terrestrial sources, and radon gas. Occupational radiation workers typically receive annual doses in the range of 1 to 5 mSv, which is considered low-dose exposure. In contrast, the radiation dose from smoking indoors can be much higher due to the concentrated inhalation of radioactive particles directly into the lungs.
Indoor smoking can also increase radiation exposure indirectly by increasing radon progeny attachment to smoke particles, which may enhance the inhaled dose of radon decay products. Radon itself is a radioactive gas that contributes significantly to natural background radiation, and its decay products emit alpha particles that damage lung tissue. Smoking indoors can exacerbate this effect by providing surfaces for radon progeny to cling to, increasing their retention in the respiratory tract.
The variability in dose estimates depends on factors such as:
– The number of cigarettes smoked daily
– The concentration of polonium-210 in the tobacco
– The ventilation and size of the indoor environment
– The duration of exposure indoors
– Individual smoking habits and inhalation depth
For example, a heavy smoker consuming 20 or more cigarettes per day indoors in a poorly ventilated space could receive an annual radiation dose from polonium-210 alone on the order of tens of millisieverts, which is a substantial addition to their overall radiation burden.
This radiation dose is highly localized in the lungs, which is why smoking is a major risk factor for lung cancer beyond the chemical carcinogens in tobacco smoke. The alpha particles emitted by polonium-210 have very short penetration ranges but cause dense ionization tracks in lung tissue, leading to DNA damage and increased cancer risk.
In summary, smoking indoors adds a significant ionizing radiation dose annually, potentially ranging from about 0.1 mSv for light smokers to over 100 mSv for heavy smokers, primarily due to polonium-210 and enhanced radon progeny inhalation. This dose is in addition to the chemical toxicity of tobacco smoke and contributes to the overall health risks associated with smoking.
