Sunburn is a burn to the skin caused by excess exposure to ultra violet (UV) radiation in the sun. It can also be caused by other sources of UV, such as sun beds. Sunburn should be avoided if possible, as even mild sunburn can damage your skin and increase your risk of skin cancer.
- You can feel the sun's heat but you cannot feel UV radiation, which is why it can still harm your skin on cool, cloudy days.
- UV radiation levels are at their peak in New Zealand from September to April, especially between 10am and 4pm.
- However, UV radiation levels can also be high when you are at high altitudes or around snow or ice.
- Even mild sunburn can damage your skin and increase your risk of skin cancer.
- You can reduce your risk of developing skin cancer by being SunSmart and covering up with clothing, a broad-spectrum sunscreen, a hat, and sunglasses.
- Remember to SLIP, SLOP, SLAP and WRAP.
Mild sunburn causes red, hot, sore skin and can usually be treated at home. See your doctor if you are badly sunburnt and feel faint, dehydrated or have severe blistering, or if a young child or baby has sunburn.
How is sunburn caused?
What is UV radiation?
The sun sends out different types of radiation, including visible light, which we can see (sunlight), infrared radiation, which we can feel (heat) and ultra violet (UV) radiation– which we cannot see or feel. People often confuse UV radiation with infrared radiation. However, UV radiation is not related to the sun's heat and can still harm your skin, even on cool, cloudy days.
Levels of UV radiation constantly change. The UV level is affected by a number of factors including closeness to the equator, time of day, time of year, cloud cover, altitude, scattering and reflection.
UV radiation levels are at their peak in New Zealand from September to April, especially between 10am and 4pm. However, UV radiation levels can also be high when you are at high altitudes or around snow or ice.
Also see the uv2Day app that shows ultraviolet index (UVI) information all over New Zealand - its peak value and it's progression throughout the day at your current location.
Who is at risk of sunburn?
The fairer your skin the higher your risk of getting sunburnt. However, skin of any colour can be damaged by UV radiation. Other factors that increase your risk of sunburn include:
- Proximity to equator – the closer you live to the equator the higher the level of UV.
- Being at high altitude – UV radiation increases 4% for every 300m increase in elevation.
- Skin exposure between 10am and 2pm – 65% of UV radiation reaches the earth between these times.
- Clear skies: clouds and environmental pollution reduce UV radiation; however, 80% of UV radiation can still get through light cloud cover, so unprotected skin can still be damaged.
- Environmental reflection – UV radiation is 80% reflected by snow and ice.
Why is sunburn harmful?
Sunburn damages the skin, causing premature ageing and increasing your risk of developing certain types of skin cancers in later years.
Sunsmart NZ provides the following warning:
The fact is that sunburn can lead to melanoma skin cancer later in life, and that skin cancer could kill you. This is true no matter what your skin type, or how much UV exposure you’ve had.
All types of sunburn, whether serious or mild, can cause permanent and irreversible skin damage. While some skin cancers are related to the number of severe sunburns the person has had (particularly during childhood and adolescence) other types may be related to their lifetime exposure to UV radiation SunSmart and Health Promotion Agency, NZ.
What are the signs of sunburn?
Signs of sunburn can vary depending on skin type and the length of time you were exposed to UV rays. The main signs of sunburn include:
- red, warm skin that is tender to touch
- flaking and peeling skin about 4 to 7 days after exposure.
Signs usually begin 3 to 5 hours after exposure to the sun's rays and are usually at their worst 12 to 24 hours after being in the sun.
In severe cases of sunburn, signs and symptoms can include:
- swelling of the skin
- a high temperature (fever) of 38ºC or above
- a general feeling of discomfort.
You may also have symptoms of heat exhaustion, such as:
How to treat sunburn?
Mild sunburn can usually be treated at home, but you should seek medical advice if:
- you are badly sunburnt and you feel faint, dehydrated or have severe blistering
- you are burnt over a large area
- a young child or baby has sunburn.
Read more about how to treat sunburn.
How can I prevent sunburn?
You can reduce your risk of developing skin cancer by using this advice Sun Protection Alert SunSmart and Health Promotion Agency, NZ.
How can I be sunsmart?
Being SunSmart is about covering up with clothing, a broad-spectrum sunscreen, a hat, and sunglasses. Remember to SLIP, SLOP, SLAP and WRAP.
SLIP into a long-sleeved shirt and into the shade. Generally, fabrics with a tighter weave and darker colours will give you greater protection from the sun. There are also certain fabrics on the market that have a SPF rating.
SLOP on plenty of broad-spectrum sunscreen of at least SPF30+. Apply sunscreen at least 20 minutes before going outdoors and reapply every two hours. Read more about using sunscreen SunSmart and Health Promotion Agency, NZ.
SLAP on a hat with a wide-brim or a cap with flaps. More people get sunburned on their face and neck than any other part of the body.
WRAP on a pair of wrap-around sunglasses. UV radiation is just as dangerous to eyesight as it is for the skin.
Sun protection alert
The Sun Protection Alert (SPA) is available from September to April (daylight savings months). It tells you what times sun protection is required for where ever you are in New Zealand.
The Sun Protection Alert is available in all daily newspapers throughout the country as well as on the MetService, SunSmart and most news websites during daylight saving months.
Information for healthcare providers
Abels, Peter, et al. Companion Statement on Vitamin D and Sun Exposure in Pregnancy and Infancy in NZ NZ Ministry of Health, 2012