What two primary characteristics define a local health effect within a small area?

Answer

Proximity and concentration dependence within a small area.

Local health effects are distinctly characterized by their strong relationship to the source of exposure, meaning that both the physical closeness (proximity) of the exposed population to the stressor and the high density or level (concentration) of the substance in that small locale are critical factors in determining the impact and subsequent adverse outcomes observed.

What two primary characteristics define a local health effect within a small area?
healtheffect