This meter, the Solarmeter 6.5, measures the level of ultraviolet radiation (UV) received from the sun. This will allow you to measure intensity of UV in sun light or to estimate the amount of protection offered by shade structures, windows and skylights. Measurements are best done on a sunny, clear day when the sun is high in the sky which is usually around midday. The Solarmeter 6.5 displays its measurements as a 'UV index'.
What is the UV index?
The UV index is a measure of the level of solar UV radiation reaching the Earth’s surface. It is an educational tool developed by the World Health Organization (WHO) to raise public awareness of the risks of overexposure to UV in sunlight. Overexposure to solar UV radiation can increase your risk of developing skin cancer and eye disorders. The UV index ranges from 1 and 11+ and alerts people about the need to adopt sun protective measures.
The higher the UV index is the greater the possibility is for sun damage to your skin and eyes and the less time it takes for harm to occur. At a UV index level of 3 and above there is a need to use sun protection. Even when the UV index is lower than 3 you should use sun protection if you are out in the sun for more than an hour.
How much UV is there in sunlight?
You can find out by using this meter. Follow these instructions to measure the UV index in full sun: (remember to hold the meter vertically, not pointing directly at the sun)
stand clear of any buildings and trees if possible so you can see the open sky
hold the meter vertically in front of your body with an outstretched arm so the sensor is pointing upwards and there is no shading over the sensor
press and hold the pushbutton to display the UV Index
you may wish to record the reading and the time of day.
This meter is particularly useful for comparing the UV levels in sunlight with the levels under a shade structure or behind a window to see how much protection is being provided.
How much UV is there under your shade structure?
To find out hold the meter vertically in front of your body with an outstretched arm so the sensor is pointing upwards and the sensor is fully shaded by the structure.
Press and hold the pushbutton to display the UV index.
How much UV comes through your window?
To find out, from inside your house, point the meter towards the window.
Press and hold the button to display the UV index.
How do I compare UV index levels?
Make a measurement in the sun then make a measurement under your shade structure or behind your window. The difference in readings will allow you to estimate how much difference the shade is making to your sun protection, for example if you measure a UV index of 10 in the sun and a UV index of 1 under your shade canopy it means that the UV level has been reduced by 10 times. Comparative measurements should be conducted within a few minutes to ensure that the weather conditions like cloud cover don’t change too much between readings.
What UV index readings can I expect?
Many factors influence outdoor UV index readings like latitude, time of day, season, haze in the atmosphere and the amount of cloud cover. Below are some typical UV index values that you can expect in different situations.
Guide to typical UV index readings (your readings may vary)
Situation
Typical UV Index values
Under a shade sail made of shadecloth*
Up to 1.5
Under a shade structure made of canvas*
Up to 1.0
Under a shady tree*
Up to 2.0
Inside a building with double-glazed windows
Up to 0.3
Inside a house with clear glass windows
Up to 4.0
Inside a car (side windows)
Up to 4.0
Inside a car (windscreen)
Up to 0.1
Outside in full sun on a clear day
Refer to the chart below
* At times when the structure is providing good shade.
Typical UV index levels on clear days in Australian cities
How do I interpret the UV index readings?
If your measurements show that the UV index is below 3 then sun protection measures are usually not required. Any time the UV index 3 or above or you are spending more than an hour outside you should consider using sun protection measures like the ones shown below to reduce your UV exposure and reduce your risk of skin cancer.
Where can I find more information about UV index and sun protection?
Should you wish to discuss the UV index measurements you have taken please contact a scientist at ARPANSA via the Talk to a Scientist program or email us.
The SunSmart website also provides a lot of information about sun protection.
