The most obvious reason is to save lives. If a person has a heart attack or other serious health problem, the quicker the patient receives help the better their chances of [a] staying alive and [b] limiting the damage to their body. There can be no greater reason for having someone on staff who knows what to do in such an emergency and can help the patient until professional medical help arrives.
CPR [a Cardiopulmonary Resuscitation Course] is a procedure that anyone can learn and apply in an emergency. This means you can assist a person – adult or child – to maintain breathing and circulation following cardiac arrest. In a serious emergency, every second counts.
But there are many other medical issues which can happen in an office. Someone can be scalded by a hot drink or cut or scratch themselves with paper, scissors, a stapler, etc. Being able to correctly stop some bleeding and then know how to dress and bandage a wound is important.
A first aid specialist can also remove dangerous situations in the office allowing prevention to be better than cure. Just making sure that the first aid kit is well stocked and readily available is another important factor and also ensure you have first aid signs pointed in the right places within the office.
Remember medical emergencies are never planned, they just happen.