The effects of sun exposure

Although exposure to the sun has beneficial effects, such as stimulating the synthesis of vitamin D in our skin, excessive exposure causes sunburn, which can ultimately lead to skin cancer4



Sunburn is acute inflammation of the skin that follows excessive exposure to UV radiation.4 UV radiation damages DNA in skin cells, resulting in redness of the skin and death of skin cells.4 Sunburn can occur within 15 minutes, and the damage that is caused is permanent, irreversible and adds up with each exposure to the sun.1

Factors that influence sunburn include:4

  • Wavelength: shorter UVB rays are the principal cause of sunburn
  • Skin type/pigmentation: people with darker skin require 3-5 times more UV exposure than those with lighter skin to cause sunburn
  • Hydration: moist skin burns more easily than dry skin
  • Reflection: UV rays are reflected off surfaces, snow, ice and sand – sunburn can occur in the shade!2
  • Ozone: decrease in ozone layer means less UV rays are filtered out
  • Altitude and latitude: UV exposure is greater at higher altitudes and closer to the equator
  • Time of day: UV exposure is greater from 10 am to 4 pm
  • Season: UV exposure is greater during summer than in winter
  • Cloud cover: clouds absorb only about 10 % of UV radiation – sunburn can occur when it is overcast!1,2

Skin cancer

Did you know that South Africa has the second highest incidence of skin cancer in the world?1 This is because of our geographic position and year-round exposure to high UV radiation.5 And everyone, regardless of racial or ethnic group, is at risk.1

Although people with darker skin are at lower risk, their skin cancer is often diagnosed at a more advanced stage and tends to occur on the palms, soles of the feet and mucosal surfaces.5

Other effects of sun exposure include:2

  • Early ageing: time spent in sun makes our skin age faster than normal, causing wrinkles, leathery skin and dark spots6
  • Lowered immune system: overexposure to the sun can suppress our immune system6
  • Eye injuries: UV rays can damage our eyes by burning the cornea and causing cataracts6

How quickly do you burn in the sun?

The Fitzpatrick chart classifies skin into 6 different types, depending on your tendency to tan, burn or both. Type I skin is light and always burns, while type VI is the darkest skin type that never burns.4 It is important to note that although people with darker skin have more protection against sun damage, everyone is at risk of the harsh African sun, therefore sun protection is paramount regardless of skin pigment.1
Type Description Skin tone
Pale white skin
Extremely sensitive skin, always burns, never tans

Example: Red hair with freckles

White skin
Very sensitive skin, burns easily, tans minimally

Example: Fair-skinned, fair-haired Caucasians, Northern Asians

Light brown skin
Sensitive skin, sometimes burns, slowly tans to light brown

Example: Darker Caucasians, some Asians

Moderate brown skin
Mildly sensitive, burns minimally, always tans to moderate brown

Example: Mediterranean and Middle Eastern Caucasians, Southern Asians

Dark brown skin
Resistant skin, rarely burns, tans well

Example: Some Hispanics, some Africans

Deeply pigmented dark brown to black skin
Very resistant skin, never burns, deeply pigmented

Example: Some Hispanics, some Darker Africans

Adapted from Australian Radiation Protection and Nuclear Safety Agency7