External environmental causes of cancer are factors in the environment that increase risk of cancer such as air pollution, UV radiation and indoor radon.

外部环境致癌因素是指环境中导致罹患癌症的危险升高的因素，如空气污染、紫外线辐射及室内的氡等。

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They do not protect against external radiation, or against any other radioactive substances besides radioactive iodine.

他们不能阻止外部的辐射、或是任何其他辐射形式。

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These are the bunkers for temporary shelter in case of contingency. One can be here for some days, controlling radiation situation in the station and keeping connection with external world.

这些是意外事故时临时避难所的掩体。人们可以在这里待几天，检查电站内的辐射情况，与外界保持联系。

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Or you can pick your poison, choosing between surgery to remove the prostate and one of two forms of radiation, external beam radiation and radioactive "seeds" implanted in the gland itself.

FORBES: Men, Cancer, & Hope

External beam radiation involves zapping a patient with high-dose X rays generated by a machine called a linear accelerator.

FORBES: Men, Cancer & Hope