However, some attribute this decline of skin cancer to the influx of darker-skinned people into Australia rather than the increase in sunscreen use. The take home message here is that sunscreens are not perfect and their protection from the sun is not complete. Protecting Yourself top 1. Sunscreen Use Guidelines Apply 30 minutes before exposure. It is only after it has time to bind to the skin that it becomes effective.
Studies show that the average person applies only half the amount necessary for sun protection.
Apply even on cloudy days. Reapply every two hours. The effectiveness of sunscreen declines rapidly. Use a sunscreen with both UVA as well as UVB protection. Sunscreens lacking these two ingredients will only protect you against a very small part of the UVA spectrum.