When a computer dies or has become obsolete, it can pollute the environment for a very long time. Computer equipment becomes obsolete very quickly. A computer will generally have a lifespan of only about 3 years. Each year, millions of old computers and peripherals which go with the computers are buried in landfill. They start to pollute the soil very soon as they contain hazardous wastes like lead.
There are recycling programmes which often will send disposed of computers overseas to countries where wages are low. In these countries, parts which have value are removed or stripped out.
The problem with recycling computers in this way is that we often simply move the pollution to another country in the world.
Much of the worlds electronic waist ends up in Asia due to lower labour costs. Much of the work of removing the wiring and separating the plastic from metal components such as circuit boards is done by hand.
Often, the plastic insulation wiring is removed by burning in low heat. This creates toxins which are released into the air and leaves ash which is filed with Dioxins.