A lot of pictures from Japan showing radiation testing with patients wearing surgical masks. The impression one gets is that they must think it is protecting them, in some way.

Is this a legitimate use of the surgical mask? How about when one just wants to avoid contracting a viral infection from the people around a person? Is there any evidence that their use actually reduces risk to their wearers?

My understanding is that surgical mask should really only prevent the person wearing the surgical mask from spreading infection. To use it to protect against radiation just seems like a bunch of nonsense.

Could someone please set me straight on this?

  • Your question muddies the waters. The current situation in Japan is not a day-to-day situation. The Japan drama tie in opening is unnecessary to the question and needlessly confuses things. Commented Mar 16, 2011 at 1:20
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    It's not about preventing radiation itself, it's about preventing radioactive dust which, as I understand, is the major hazard in nuclear accidents. However, it'd be quite interesting to know whether the masks are actually any use even against that. Commented Mar 16, 2011 at 9:01
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    Are there sources from within or from outside Japan telling you the masks are for personal protection from radioactive particles rather than against the wearer spreading their own cold and flu infections? Or have you made that assumption yourself? Commented Oct 17, 2012 at 10:38
  • Related (closed) question on Travel.SE: Why do the Japanese wear masks like Surgeons in Tokyo? Commented Oct 17, 2012 at 10:39

2 Answers 2


Asia Surgical Masks Image Source

Japanese (and other asians) wearing surgical masks is a common practise that predates the Fukushima accident.

Regarding radioactive radiation:

No, a thin piece of paper will not protect you, except maybe Alpha radiation:

Protecting yourself from external exposure to alpha radiation is easy, since alpha particles are unable to penetrate the outer dead layers of skin or clothing.

However, tissue that is not protected by the outer layer of dead cells, such as eyes or open wounds, must be carefully protected.


  • Greater concern about beta particles. They can burn the skin in some cases, or damage eyes.
  • Greatest concern is about gamma radiation. Different radionuclides emit gamma rays of different strength, but gamma rays can travel long distances and penetrate entirely through the body.

Gamma rays can be slowed by dense material (shielding), such as lead, and can be stopped if the material is thick enough. Examples of shielding are containers; protective clothing, such as a lead apron; and soil covering buried radioactive materials.

Wearing a surgical mask may however help against inhaling radioactive dust. It depends on how fine the dust is. But some protection is still better than no protection.

Regarding viral infection:

WHO - Advice on the use of masks in the community setting in Influenza A (H1N1) outbreaks (2009)

In health-care settings, studies evaluating measures to reduce the spread of respiratory viruses suggest that the use of masks could reduce the transmission of influenza.

In the community, however, the benefits of wearing masks has not been established, especially in open areas, as opposed to enclosed spaces while in close contact with a person with influenza-like symptoms.

Nonetheless ... using a mask can enable an individual with influenza-like symptoms to cover their mouth and nose to help contain respiratory droplets, a measure that is part of cough etiquette.

Using a mask incorrectly however, may actually increase the risk of transmission, rather than reduce it.

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    Considering they're concerned about the radiation spreading with the wind, it's indeed the radioactive dust they are worried about. (Radiation by itself doesn't of course care about the wind.) Commented Mar 16, 2011 at 8:55

A surgical mask is designed to protect the patient from the germs of the surgical staff. They are actually rather ineffective as personal protection. What they are good at is stopping germs from coughing and sneezing.

A better solution would be a paper construction filter. It would at least filter out larger dust particles that have deposited radioactive particles on them.

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