How long does it take for a plastic bag to break down?


We don’t know how long it takes for plastic bags to fully break down into organic matter - some estimate 1000 years - because we’ve only had plastic retail bags in widespread use since the 1970s. It would likely take longer for bags to break down in a landfill (in a tightly-compacted landfill space, the lack of light and air prevents the decomposition process).