We take a look at how the world's richest man now owns nearly $3 billion worth of Twitter stock. Elon Musk recently bought a 9.2 percent stake in the company, making him the top shareholder. But the Tesla founder, who has 80 million Twitter followers, has not refrained from criticising the platform. Also, the United Nations says that 99 percent of the world's population breathe in dirty air, although the problem is much worse in poorer countries. Finally, US toymaker Mattel says it's going to produce greener toys.