Transmission through a dielectric - no absorption. Increase distance from the source. Limit time of exposure. Utilize frequencies which are less hazardous. Health effects vary with type of radiation.
Many sources emit a variety of frequencies.
IH must decide which will be measured and controlled. Penetration is limited - target organs are the skin and cornea , although the immune system may also be affected. UVB or Actinic UV, the mid-frequencies, are the most damaging. Intense acute exposures, and possibly less intense cumulative exposures can cause cataracts. The TLV is designed to protect against thermal retinal injury.