As per recommendations published in the British Medical Journal, consumers are advised to apply sunscreen using the following guidance. To gain the sun protection advertised on the tube, you should squeeze out two lines of sun cream along the full length of the underside of your index and middle fingers. This amount should then be applied to EACH of the following areas every 2 hours and after swimming: - Head, neck and face - Left arm - Right arm - Upper back - Lower back - Upper front torso - Lower front torso - Left upper leg and thigh - Right upper leg and thigh - Left lower leg and foot - Right lower leg and foot. If you do not apply this much, please be aware that the sun cream may not reach its advertised efficacy. Please note that this guidance applies to all sunscreen, not just that from Green People.