The other day, I stopped by the organic supermarket in my neighborhood to grab a few groceries for the week. As I waited in the checkout line, I noticed that the lady ahead of me had brought along a canvas tote to lug her groceries home with minimal environmental damage.

I glanced over at the next checkout aisle and saw a scruffy-looking young couple who radiated patchuoli and vegan goodness. They also had enough foresight to bring in a couple of mesh bags.

"You saved 25 cents today ma'am," the cashier told the lady in front on me, as he packed her groceries in her tote. The two of them exchanged a warm, we're-doing-right-by-the-planet smile and then the woman looked over to study a sign by the door.

I'm in this store a few times a week, but this was the first time I noticed a huge poster by registers, reminding shoppers to bring their own bags. If you B.Y.O.B., you'll save a little spare change and if you want, you can donate the change to your the charity of your choice.

"Donate my quarter to the Nature Conservancy," she said, with just enough self-satisfaction to make me jealous.

Then, it was my turn at the register. "Paper or plastic?" asked the cashier. Was it my imagination, or did he shoot me a "geez, you sure are wasteful" smirk as he asked the question?

"Uhh," I stammered, as I frantically tried to remember which one did less damage to the environment. "Paper, I guess?" I told him, sounding not at all sure of myself.

Later, when I got home, I Googled paper and plastic, and learned that I had picked the worst offender. Both paper and plastic are bad for the environment, considering that both wind up in landfills and take years (if not centuries) to breakdown. Still, it truly is a debatable issue.

In the final analysis, however, plastic bags seem to be slightly better for the planet. Producing them consumes 40 percent less energy and generates 80 percent less solid waste than paper bags. Plastic bags can also be recycled easily, by returning them to the grocery store. Reusing any bags (or going without, when possible) can have a dramatic impact on the environment; We use way too many bags.

The whole experience convinced me to stash a couple canvas totes in the backseat of my car. That way, the next time I'm in the checkout line, I'll B.Y.O.B and maybe sound a little smug when I tell the cashier to donate my change. Who knows, maybe it'll inspire some other unsuspecting schmuck to bring their own bags, too.