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this is especially for the old people , since they have less abilities than young people to focus on the job due to their health ....
driving is one of the common activity  , where we can see many of accidents & incidents happens because of the age .... 
Old people can have easily fatigue , dizzeness , due to diabetes as an example , according they might lose focus ...and cause accidents .
 

Old or young age can play a major role in the safety performance.
It is well known in the safety field that young people cause many accidents at work due to lack of experience, carelessness and over enthusiasim.
Some studies suggest that young drivers cause more traffic accidents than older ones (Carter, T.
(2006).
Fitness to drive: A guide for health professionals.
London: Royal Society of Medicine Press Ltd.).
However, old age is also known to have its own disadvantages when it gets to safety as it is usually associated with high blood pressure, diabetes, heart problems, obesity, musculoskeletal problems, mental fatigue etc.
which can affect the individual's performance and may affect others if he/she is carrying out a safety-critical task.
In conclusion both young and old age can have an effect on the safety...
and it should be considered carefully when designing for safety.