Where does a plastic bottle come from, and where does it go when we throw it away?

In numbers

• ≈ 9%of plastic waste up to 2015 that was recycled
• ≈ 79%that piled up in landfills or nature
• 1973the PET bottle was invented

In five stops

1. 1

   Where were its atoms born?

   PET is made of carbon, hydrogen and oxygen atoms. The hydrogen is left over from the Big Bang; the carbon and oxygen formed inside stars.

2. 2

   How did nature prepare it?

   The bottle's carbon and hydrogen came the same way as gasoline's: millions of years ago, plankton and algae in the sea captured carbon by photosynthesis; when they died they were buried on the sea floor, and heat and pressure underground turned them into oil and natural gas.

3. 3

   What did people do?

   Substances from oil and natural gas are turned into two small molecules, ethylene glycol and terephthalic acid. These are linked thousands of times over to form the long chains called PET. PET was patented in England in 1941, and the PET bottle was invented in 1973. In the factory, PET is melted into a small tube, then heated and blown up with air inside a mould.

4. 4

   What happens when we use it?

   The bottle is light, hard to break and watertight, which is why it is used so much. But most bottles are used only once and thrown away.

5. 5

   Where does it go next?

   Collected PET bottles are shredded, washed, melted and made into new bottles or polyester fibre. Those not collected build up in landfills or in nature, where sunlight and waves break them into tiny pieces called microplastics. If burned, their carbon enters the air as carbon dioxide. Of the plastic waste generated up to 2015, about 9% was recycled, 12% was burned and 79% piled up in landfills or the environment.