Many eco-conscious, forward-minded thinkers would be shocked to discover they’re actually doing harm to the planet every time they toss something into the recycling bin at work. After all, as long as you’re throwing the item into a container labeled with those three curving arrows, haven’t you done all you can?

Unfortunately, no. Much of the problem stems from the fact that people, in their eagerness to help the environment, are failing to be discerning in their recycling habits. While the impulse to reduce, reuse and so on is important, it’s equally important to be sure you’re doing it correctly. Otherwise, you could be harming more than you’re helping.

Let’s take a look at five of the biggest “recycling sins” and how you can rectify the problem posthaste.

1. Tossing Plastic Bags

While plastic bags might seem like a good addition to the plastic bin at work, they aren’t for a number of reasons. For one thing, they easily get caught in the sorting machines at recycling centers, gumming up the works and making those centers lose valuable time. For another, they aren’t the right grade of plastic, and have to be sorted out anyway. Instead of following that impulse, separate your bags out and send them to a special plastic film recycling center.

2. Recycling Greasy Paper

Greasy paper should no longer be considered paper. Pizza boxes, paper plates and crumpled napkins might be made of the same pulp paper’s made of, but they’re soaked in oils. When recycling plants go to turn that old paper back into pulp for new paper, the oil gets released and floats around in the pulp as it’s being processed. The result is paper that can’t stick together and set. You’ve just ruined a whole batch with one pizza box. Don’t do it.

3. Failing to Sort Out Plastic Caps

Plastic caps are not recyclable at recycling stations. They’re made of a different grade of plastic than is usually accepted – No. 5. Even when No. 5 is accepted, it’s usually in the form of more pliable yogurt or sour cream containers, not those hard caps. Luckily there’s an outlet that does take them: Gimme 5 Caps Recycling, which has partnered with Whole Foods to bring you dropoff locations throughout the country.

4. Recycling Shredded Paper

Paper is paper, right? So why not throw shredded documents into the recycling bin? It seems like a two-for-one, protecting confidential information and still saving the planet. Unfortunately, as Earth911 explains, when you shred paper, you destroy the long fibers that make it valuable. These fibers are what make paper strong and durable, and when you mince them up in a shredder, it makes for pretty useless pulp. Adding to the problem is the fact that you then degrade the quality of an entire batch of paper, even if some of it wasn’t shredded.

5. Including Broken Glass

While it’s tempting to make sure each teeny piece of that bottle you broke gets scraped up and put into the glass recycling, this is the wrong approach. After you put it in the bin, glass is sorted by color, broken down and turned into new bottles. When you put tiny pieces into the bin, it’s hard to tell clear from brown from green, and you work against the process. From now on, recycle only whole bottles.

Recycling at work isn’t meant to be a minefield. If you’re ever unsure, you can always look something up online, or ask your work’s recycling solutions provider for an exact answer. Here at Recycle Away, for instance, we’re always happy to answer any questions about how to do right by the planet, so never hesitate to ask.