Attempting to shore up a battered image and looking to reduce one of the major sources of pollution it creates, Wal-Mart said Friday that it would be cutting back on its use of plastic bags, aiming for a full 33 percent reduction by 2013.

Though plastic bags are recyclable, collection centers can be hard to find. The thin and easily-torn plastic material seldom has much reuse value, and generally ends up in landfills, where it breaks down into smaller pieces, frequently finding its way into the ocean.  Wal-Mart’s cuts could lead to a reduction of some 135 million pounds of plastic overall.

While some cities, most notably San Francisco, have banned non-biodegradable plastic bags entirely, a phase-out or reduction plan from the corporate side is likely to be more effective and easier to enforce. 

Currently, workers at many major retailers are trained to automatically bag goods without first asking the customer if they have a bag with them, or would simply prefer to carry the products by hand.  The simple step of creating the choice in the customers mind could save millions of bags.