Up to 140,000 people a year die from a first aid emergency situation. However, they might have been saved if first aid had been available to them, says St John Ambulance in a powerful new campaign. But fewer than one in five of us know even the basics. Admittedly, it can be scary pounding on a stranger’s chest, and then there is the thought that you may harm them by doing it wrong? St John Ambulance says that there are five main life-threatening events for which we should all be able to give first aid. These are when someone is choking, has severe bleeding, is having a heart attack, is unconscious and breathing or is unconscious and not breathing.

As you are giving first aid, it is important to try and remember to talk to the person and not just treat them like a mannequin. They can probably hear you so be supportive and encouraging.

Giving first aid is about trying to keep someone alive until professional help arrives. For the severe problems listed here, you only have three to four minutes to start your first aid or the person could die.

If you think someone needs first aid because they seem to be unconscious, try calling out to them or rubbing the centre of their chest to see if they are responsive. Contact the emergency services i.e. 999 or 112. It is advisable to place the casualty in the ‘Recovery Position’ (lying on their side with the upper leg’s knee and hip bent at right angles and the casualty’s head tilted back so the airway is open). If the person is breathing and unconscious, and you think they might have a spinal injury, then do not move them unless there is imminent danger which forces you to carefully move them.

If someone is bleeding heavily from an arm or leg you should call for help and put firm pressure on the wound with your palm. Raise the arm or leg, gently, with support, higher than the heart to reduce blood loss. Tourniquets are controversial and there is some evidence that when used by first aiders they increase blood loss by occluding the veins more than the arteries, therefore do not attempt using them.

If someone is unconscious and not breathing, you will need to start Cardiopulmonary Resuscitation (CPR). Interlock your fingers and place the heel of one hand on the centre of the person’s chest. Press down so you can feel the ribs move down by 5-6cm and repeat at a rate of 100-120 a minute. There is a helpful video on the NHS website of Vinnie Jones explaining CPR to the song Stayin’ Alive by the Bee Gees which best matches the rate needed. CPR moves oxygenated blood (blood rich with oxygen) around the body and to the brain, but it will not usually restart the heart. A defibrillator is needed, which some communities have in shops, hotels, airports and leisure centres.

Remember: in most cases you are more likely to help than do harm.