Hair, surprisingly, offers very little protection from harmful UV rays

Melbourne, Sept 13: 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. (ANI)

Phasing out coal emissions might help fight global warming

Washington, September 13: A team of researchers have determined that the ongoing rise in atmospheric carbon dioxide (CO2) from burning of fossil fuels might be kept below harmful levels if emissions from coal are phased out within the next few decades.

The research has been carried out by climatologist Pushker Kharecha and James Hansen, director of NASA Goddard Institute for Space Studies.

According to them, less plentiful oil and gas should be used sparingly as well, but that far greater supplies of coal mean that it must be the main target of reductions.

The burning of fossil fuels accounts for about 80 percent of the rise of atmospheric CO2 since the pre-industrial era, to its current level of 385 parts per million.

However, while there are huge amounts of coal left, predictions about when and how oil and gas production might start running out have proved controversial, and this has made it difficult to anticipate future emissions.

To better understand how the emissions might change in the future, Kharecha and Hansen considered a wide range of scenarios.

"This is the first paper that explicitly melds the two vital issues of global peak oil production and human-induced climate change," Kharecha said.

"We found that because coal is much more plentiful than oil or gas, reducing coal emissions is absolutely essential to avoid dangerous climate change," he added.

CO2, which accounts for about half of the human-caused greenhouse gases in the atmosphere, concerns scientists because it can remain for centuries.

To better understand the possible trajectory of future CO2, Kharecha and Hansen devised five emissions scenarios spanning the years 1850 to 2100.

Each reflects a different estimate for the global production peak of fossil fuels, the timing of which depends on reserve size, recoverability and available technology.

The first scenario estimates CO2 levels if emissions from fossil fuels follow "business as usual," growing 2 percent annually until half of each reservoir has been recovered. After this, emissions begin to decline by 2 percent annually.

In the second scenario, emissions from coal are reduced, first by developed countries starting in 2013, and then by developing countries a decade later, leading to a global phaseout of emissions by 2050.

The phaseout could come either from reducing coal consumption or by capturing and trapping CO2 from coal burning before it reaches the air.

The remaining three scenarios include the phaseout of coal, but consider different scenarios for oil use and supply.

"We're illustrating the types of action needed to get to target carbon dioxide levels," Kharecha said.

"The most important mitigation strategy we recommend-a phase-out of carbon dioxide emissions from coal within the next few decades-is feasible using current or near-term technologies," he added. (ANI)