A full head of hair provides very little protection for your scalp from harmful UV rays, says a new study published in the journal Photochemistry and Photobiology.
The study's researchers claim that a large number of melanomas occur on the scalp, with one study showing they make up 13 percent of melanomas.
"So the question arose how UV penetrates through the hair," ABC Science Online quoted Parisi, as saying.
To reach the conclusion, the research team studied how much ultraviolet (UV) radiation from the sun got through to the scalp with a full head of hair.
They placed a UV sensor in the centre of the top of the head of a mannequin adorned with a wig made of human hair. The researchers then tested how much UV got through when the sun was at different positions in the sky.
"It started about 9 o'clock in the morning right through to lunch time," said Parisi.
They also tested what happened when the head was upright or tilted towards the sun, and what happened under the shade of a beach umbrella.
They also tested the impact of grey and brown hair, and short (4.9 centimetres) and long (10.9 centimetres) hair.
They found that the colour of the hair made no difference, but that short hair may provide marginally more protection than long hair.
Parisi thinks this is because long hair weighs itself down at the part and exposes more of the scalp to sun.
Overall, the researchers found hair offered a protection factor ranging from 5 to 17, which is significantly lower that the average sunscreen, which offers a protection factor of 30.
"This is much lower than properly applied sunscreen. I'm surprised that the protection factor is so low," says Parisi.