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Exposure in epidemiology

The condition of being subjected to something, as to infectious agents, extremes of weather, or radiation, which may have a harmful effect.

  • In case of communicable disease:
    • Negative exposure – Consumption of polluted water causes disease
    • Positive exposure – Consumption of safe water does not causes disease
  • In non-communicable disease:
    • Smoking is a risk factor for heart disease but if do not smoke then it is not ensured that there will be no heart disease


  • Study 1: two group-smokers and non smoker-to find out the relation of smoking with heart disease – observational study
  • Study 2: All smoker – one group stop smoking and other group continue smoking – to find out the outcome of stop smoking – experimental study