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