Most people are now aware that excessive exposure to the sun and sunburn can lead to skin problems, some as serious as skin cancer.
Sunburn should always be avoided and especially so with children. Unfortunately many people assume that a T-shirt is good enough for protecting them or their children's skin from the sun, but sadly this is often not the case.
Most clothing offers some form of sun protection but this is generally not adequate to provide sufficient protection against UV radiation. A typical summer T-shirt would probably offer a UPF rating of somewhere between 7 and 15 +, much less when wet, significantly below the minimum recommended levels.
The sun's rays are strongest between 10 a.m. and 4 p.m, so whenever possible, limit exposure to the sun during these hours.
What Makes A Good Sun Protection Garment?
Composition of the fabric
Different fibres have different natural UVR absorbing properties.
The tighter the weave the higher the level of Sun Protection. The combination of high UVR absorbing fibres and a tightly woven fabric creates a good sun protective garment.
E.g.: Loosely woven light cotton T-shirt will have a lower sun protection to a tightly woven lycra.
Well fitting garments are very important. Over stretching may decrease the UPF rating, in the same way that a lycra suit that is too tight will degrade more quickly in chlorine.
Some fabrics have a lower rating when wet. Dependent on the type of fabric and the amount of moisture absorbed. E.g.: A cotton T-shirt will absorb a lot of moisture whereas a nylon/elastane sun top does not absorb moisture at all. The nylon/elastane will maintain it's UPF rating when wet whilst a cotton T-shirt will not.
The more body coverage the greater the sun protection.
Whilst certain dyes can absorb more UVR, the fibre content and weave density is more important. E.g.: A White nylon/elastane shirt can have a much higher rating then a Black cotton voile shirt.
Old, worn, threadbare or faded garments may have a low UPF rating.
Comparison Of Sun Rating Protections
UPF / SPF Rating
Approx % UV Blocked
Very Good UV Protection
25, 30, 35 / 25, 30
96.0% - 97.4% / 96.0 - 97.4%
Excellent UV Protection
40, 45, 50, 50+ / 30 +
97.5% - 98.0% / 97.5+%
Understanding The Jargon
What Is UVR? UVR Stands for Ultraviolet Radiation and is present in sunlight. UVR is classified as UVA, UVB and UVC. Over exposure to solar radiation can cause skin damage and an increased risk of developing skin cancer. The most obvious short term effect of over-exposure to UVR is sunburn. Cumulative exposure to UVR particularly during childhood increases the risk of cancer development as an adult
What Is UVI? UVI stands for Ultraviolet Index and measures the highest UVR level reached each day at a particular location. The ozone layer shields the Earth from harmful UV radiation. Ozone depletion, as well as seasonal and weather variations, cause different amounts of UV radiation to reach the Earth at any given time.
Developed by the National Weather Service (NWS) and EPA, the UV Index predicts the next day's ultraviolet radiation levels on a 1-11+ scale, helping people determine appropriate sun-protective behaviours.
UPF & SPF Scales
This is the maximum Ultraviolet Protection Factor accorded to sun protection clothing by Australian, New Zealand and US Government rating agencies. The UPF rating indicates how much Ultraviolet Radiation is absorbed by the fabric. For example a fabric with a UPF Rating of 50 only allows 1/50th of the hazardous ultraviolet radiation falling on the surface of the fabric to pass through it - or expressed another way, the fabric blocks 98% of the sun's harmful UV Rays. This means that, where it is protected by the fabric, the fabric will reduce your skin's exposure to ultraviolet radiation by twenty times. Not to be confused with SPF which is applied to sunscreens to measure the amount of protection provided against UVR.
The new UPF fabric rating also requires that fabrics claiming to be sun protective must be prepared in the following ways before testing:
- Undergo 40 simulated launderings
- Be exposed to 100 fading units of simulated sunlight (equivalent to 2 years light exposure)
- And, if intended for swim wear, exposure to chlorinated water
Sun Protection Factor which is the number is determined experimentally indoors by exposing humans to a light spectrum meant to simulate midday sun. Some subjects wear sun cream and others do not. The amount of light that induces redness in sun cream protected skin, divided by the amount of light that causes redness in unprotected skin is the SPF. It is mainly a measure of UVB protection and ranges from 1 to 45 or above.
A sunscreen with an SPF of 15 filters 92% of the UVB. Put another way, a sunscreen with an SPF of 15 will delay the onset of a sunburn in a person who would otherwise burn in 10 minutes to burn in 150 minutes. The SPF 15 sunscreen allows a person to stay out in the sun 15 times longer.
There is currently no uniform measure of UVA absorption. There are broad-spectrum sunscreens that protect against UVA and UVB radiation although it is important to remember that the SPF does not predict UVA protection. The UV Index is a public health education tool reported by meteorologists. It offers a daily report of UV light levels on a scale from 1-10+.
The "protectiveness" of clothing can also be measured by SPF. The following are SPF's of various types of clothing:
- Nylon Stockings - SPF 2
- Hats - SPF 3-6
- Summer-weight clothing - SPF 6.5
- Sun-protective clothing - up to SPF 30