UVA rays have a relatively long wavelength, meaning 95% of UVA radiation reaches the earth's surface. Present all year round, even on gloomy days, they penetrate clouds, glass and the epidermis. Although painless, they can penetrate the deeper layers of the skin, to reach the heart of the dermis cells. UVA can damage cell's DNA, cause sunburn, inflammation, sun allergies and pigment problems. It's also the primary culprit when it comes to ageing skin: it weakens collagen network loosens the skin, reduces firmness and causes wrinkles.