Exposure

• a natural or artificial section or cut into the ground, such as a wind blow-out, sea-cliff, or roadcut.
• the orientation of a site in relation to magnetic direction or the sun - e.g. a "southern exposure".
• the quality of color, contrast and light in a photograph.
• Being exposed to ionizing radiation or to radioactive material. Source: U.S. Nuclear Regulatory Commission
• The amount of radiation or pollutant present in a given environment that represents a potential health threat to living organisms.
  Source: Terms of the Environment