The Green Lantern

“Wait, Does This Go in the Recycling Bin?’

What to do when you forget the rules.

I wonder about this one when I’m sorting kitchen waste: If you don’t know whether something is recyclable, what’s the best approach? Is it better to put the inscrutable item in the blue recycling bin, or should you just throw it in the trash?

Although it may seem sacrilegious—since being an ardent recycler is the sine qua non of old-school environmentalism—when in doubt, you should throw it out.

What happens if you try to recycle something that isn’t accepted in your area? In the best-case scenario, the end buyer isn’t too bothered by its presence and just uses it along with the salvaged material he did want. For example, a No. 5 polypropylene yogurt cup that ends up in a batch of No. 2 high-density polyethylene (aka HDPE) won’t present much of a problem—the mixing process will be a little more complicated, since melted polypropylene is runnier than melted HDPE, but the two plastics aren’t chemically incompatible. (Lots and lots of yogurt cups, however, would pose more of a problem.)

Trash or recycling?

In the moderately bad scenario, the offending item gets weeded out by the recycling facility’s sorters, in which case it will be landfilled or incinerated—exactly what would have happened if you’d thrown it in the trash in the first place, except for the extra money and fuel spent on its roundabout journey.

In the worst-case scenario, the interloper either damages equipment or ruins a batch of otherwise valuable material. Polyvinyl chloride (which is rarely accepted curbside) and polyethylene terephthalate (which almost always is) provide the classic example of plastics that don’t play well together: A single pound of No. 3 PVC can wreck10,000 pounds of No. 1 PET. Other things to avoid throwing in the blue bin unless you know for a fact that they belong there: noncontainer glass (like mirrors), Pyrex, plastic bags and films, aluminum pots and pans, and crockery.

Meanwhile, what happens if you throw away a recyclable item? Well, you’ve certainly wasted an opportunity to conserve resources and save energy. However, the direct impacts of throwing away a single item aren’t likely to be devastating. Hauling that misplaced box or bottle to the dump does require fuel, which contributes to global warming. And in a packed landfill, decomposing organic materials like wood or paper can spew out methane, a particularly potent greenhouse gas. According to the EPA’s life-cycle analysis of waste management options, a pound of mixed plastic sent to a landfill will produce average net emissions of 0.04 pounds of carbon dioxide equivalent—or about as much as 0.002 gallons of gasoline. A pound of mixed residential paper, meanwhile, will produce 0.25 pounds of CO2-equivalent. As long as your local landfill isn’t overflowing, throwing away a recyclable is a minor environmental sin. (However, it could get you slapped with a fine—another good reason to print out your local guidelines and post them on your fridge.)

The next time you find yourself hovering indecisively over a set of trash bins, here are some rules of thumb. Plastic bottles and jugs marked No. 1 or No. 2 are virtually guaranteed to be accepted, so go ahead and toss them in with your recycling. *  Newspaper, corrugated cardboard, magazines, and office paper are almost always good to go as well. If your mystery object doesn’t fall into one of those categories, trash it.

If your community participates in single-stream recycling—where everything from bottles to cans to cardboard boxes get placed in one curbside bin—it might be tempting to err on the side of tossing your mysteryitem into that bin as well. It’s all going to get sorted out in the end, right? But there’s an argument to be made that single-stream recycling actually requires more diligence from consumers—contamination rates often rise dramatically in these programs, so anything you can do to keep unwanted items out of the mix will make the system more efficient.

Is there an environmental quandary that’s been keeping you up at night? Send it to, and check this space every Tuesday.

Correction, Feb. 16, 2010: The original sentence stated that all plastic items marked No. 1 and No. 2 are virtually guaranteed to be accepted. (Return to the corrected sentence.)