= Solution
\b[Reduce time, increase distance and use radiation-appropriate shielding.] At fixed conditions, accumulated <absorbed dose> is proportional to exposure time. For an approximately isotropic point source, the <inverse-square law> reduces the uncollided radiation field as distance increases. Confinement of radioactive material prevents contamination; it addresses a different pathway from attenuation of an external field.
For <alpha particles>, short stopping ranges make light barriers sufficient against external particles, but confinement remains important. For <beta particles>, a low-<atomic number> shield such as plastic limits both penetration and secondary <bremsstrahlung>; high-<atomic number> material can then attenuate residual photons. For penetrating <gamma rays>, dense material such as <lead>, or a thicker bulk shield such as concrete, provides attenuation. \b[One shield material is not equally appropriate for every radiation type.]<Minimize Your Exposure by United States Nuclear Regulatory Commission>[Time, distance and shielding; alpha, beta and gamma examples]{ref}<Consolidated Guidance About Materials Licenses, Volume 12 by United States Nuclear Regulatory Commission>[Appendix I, printed page I-2: low-atomic-number beta shielding and an outer high-atomic-number layer for bremsstrahlung]{ref}
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