Researched and written by Mike Shertz, MD/18D, not AI
In a radiological event, the primary risk of internal contamination comes from inhaling or ingesting radioactive particles. While 𝜶 radiation cannot penetrate a uniform or intact skin, these particles cause significant cellular damage once they enter the lungs or are swallowed.
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Ionizing radiation is comprised of 𝜶 and β particles, and 𝜸 rays. 𝜶 particles are blocked by less than 1/10 of a millimeter of intact skin / human tissue. However, they can cause significant radiation exposure to internal organs if ingested or inhaled. This can result in increased cancer risk at best, and death from acute radiation syndrome at worst, if the exposure is significant enough.
β particles can penetrate through several millimeters of biological tissue on their own. 𝜸 rays require substantial shielding to block their effects.
In the event of a nuclear detonation or accident, both the National Council on Radiation Protection and Measurements, as well as the US CDC, recommend the public use face masks as protection against inhaling / ingesting radioactive material / contamination when they can’t immediately get inside.
A Taiwanese study evaluated seven commonly available face masks bought from a “local chain store” for their ability to block 𝜶 and β particle penetration.
Attenuation was defined as the percentage reduction of inhaled 𝜶 and β particles through the tested mask as measured by Geiger-Mueller counter and surface barrier detector.
All tested mask materials blocked at least 90% of 𝛼 particle radiation and several mask types blocked 100%. Although a polyester fiber, rayon fiber, and N95 mask all showed 100% reduction, if you were buying a mask in a store, only the N95 would be easily identifiable / labelled as to its construction and therefore, reduction abilities.
Unfortunately, none of the masks were effective at significantly reducing β particle exposure.
Tested 𝜶 particles included Am-241, Cm-244, and Pu-239. The β source was Sr-90.
Americium 241, an 𝜶-emitter, is present in household smoke detectors. In 2004, a London terror cell collected thousands of smoke detectors to harvest the radioactive material in preparation for a radiological dispersion device or “dirty bomb.”
If you are forced to use a “face mask” in an ionizing radiation exposed situation, an N95 mask is your best for protection against ingested / inhaled 𝜶 particles.
Wu H, Liu HD, Lin TH, Lin MW. Measurements of face mask’s capability to block ionizing radiation. Sci Rep. 2025 Feb 22;15(1):6516. doi: 10.1038/s41598-025-89643-4. PMID: 39987210; PMCID: PMC11846965.
