"Mature markets such as the United States, Western Europe, and Japan currently account for 58 percent of the world’s installed PCs, but these markets only account for 15 percent of the world’s population," said George Shiffler, research director at Gartner.

"Rapid penetration in emerging markets is being driven by the explosive expansion of broadband and wireless connectivity in these markets, the continuing fall in PC average selling prices (ASPs), and the general realization that PCs are an indispensable tool for advancement, " said Shiffler.

The global PC market is being driven by users who replace their old machines with new ones. Some of the old PCs find their way back to second owners, some are recycled and others end up in a landfill.

"We forecast just over 180 million PCs – approximately 16 percent of the existing installed base – will be replaced this year," said Meike Escherich, principal research analyst at Gartner. "We estimate a fifth of these, or some 35 million PCs, will be dumped into landfill with little or no regard for their toxic content.

"It will become an even more pressing issue, especially in emerging markets, as the number of retired PCs grows with the continuing expansion of the PC installed base."