Figuring out which plastics you can recycle can be confusing. Most of us feel like we’re being earth-conscious when we toss something in the recycling bin, right? Well, it turns out you just might be doing more harm than good. How so? Fact is that if you include some unrecyclable items in your bin, you run the risk of the entire batch being re-routed to the nearest trash dump.

Via Yahoo Green, here’s a list of some common items that don't belong in the recycling bin, no matter what your zip code:

• Pizza boxes. The oil from pizza can contaminate cardboard boxes, making it impossible to process them into clean paper.
• Napkins and paper towels. It's not the paper goods themselves that present a problem, but the fact that they're typically used to wipe up food, cleaning products, and other "hazardous waste."
• Sticky notes. Their size, color, and the adhesive strip make them a better bet for the trash bin.
• Plastic caps. Curbside programs won't recycle them, but Aveda collects them and turns them into packaging for new products.
• Wet paper. Paper fibers that have been exposed to water are shorter and therefore less valuable to paper mills, making it unprofitable to collect and recycle.

Another thing you may want to keep in mind is that while it’s generally well known that most curbside programs only take plastics labeled #1 and #2 on the bottom, many people are shocked to hear that shape sometimes plays a role. For example, many communities don't accept tubs (mouth wider than base), but will take bottles (base wider than mouth) even if the numbers are the same because these plastics are manufactured differently, says Darby Hoover of the Natural Resources Defense Council.
Check in with your local waste or sanitation department to find out what the specific rules are in your area. And for more facts on recycling and what you can do to take action, check out our Recycling page.