The ozone layer can absorb some harmful UV rays and help to protect humans from its harmful effects. Unfortunately, some of the rays still penetrate through the ozone layer and enter the Earth’s atmosphere and harm us. This is why it is important to use sun protection such as sun block or sunscreens. The amount of sun protection factor recommended has been studied and mainly categorised by the time spent outdoors and the skin tone, as seen from the SPF selection guide below. Higher SPF required is usually for longer hours spent outdoors and for fairer skin tones.