Breathing the air in New Delhi is equivalent to smoking 45 cigarettes a day.
The three richest Americans – Bill Gates, Jeff Bezos and Warren Buffett – have as much money between them as the 160 million poorest Americans.
A supernova that has been observed to explode again and again over 60 years is challenging everything astronomers thought they knew about the death of stars.
Danish researchers have discovered that having a cat in the house halves the chances of newborn babies developing asthma.
British biologists have discovered that wounds such as cuts and burns acquired during the day heal 60% faster than those sustained at night.
A seven-year-old boy has made a complete recovery after being given an entire new skin grown from stem cells in the laboratory.