Ever wondered if "Ban the Bag" is fully justified? Well, there's a fascinating report from the Environment Agency that goes a long way to explaining just how we should treat alternatives if our behaviour is to have a positive effect. The report assesses the lifecycle impacts of standard one-use plastic bags and a number of alternatives. It shows that the enviromnetal impact is dominated by resource use and production with transport, secondary packaging and end-of-life management having relatively minor impacts. One interesting way to grasp the impacts is given in the form of a table showing how often alternatives have to be used in order that their impact is lower than a one-use bag. For instance, assuming that the base carrier is genuinely single use (e.g. not subsequently used as a big liner) then a paper carrier would have to be used 3 times for its impact to be lower; for a low density polyethylene 'bag for life' this rises to 4 uses; then for a more durable non-woven polypropylene bag the required uses are calculated at 11; and for a cotton bag we reach an amazing 131 uses. If you assume that 40% of single use bags do actually get used for something else, such as a replacement bin liner, then re-use requirements for other bags, of course, rise. In the case of the cotton bag this is now 173! (I guess I'll just have to carry on with all those cotton bags that my wife dislikes!).
The report does not consider some impacts, such as littering, or the impacts of degradable polymers in the recycle stream. Never-the-less, from my, admittedly cursory, glance this appears to be a pretty thorough piece of work providing plenty of food for thought.
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