In our callout for greener gifting ideas, some readers suggested gift certificates for things like a show, a restaurant or, more traditionally, a store. Gift cards can be a great last-minute option, and they're very popular — in fact, they were the most popular holiday gift in a recent online survey of Canadians, more than half of whom planned to buy gift cards for their loved ones. But they, too, have an environmental impact. Many gift cards are made of PVC plastic, which is hard to recycle and isn't accepted by most recycling systems. While they're small and slim, their popularity means they add up — in 2014, two billion gift cards were purchased in the U.S. alone, according to an estimate by the consulting firm A.T. Kearney. Giftrocket, a company that offers e-gift cards, estimates that each physical card contains about five grams of PVC and generates 21 grams of CO2. That means in total, gift cards created 10,000 tonnes of PVC waste and 42,000 tonnes of CO2 in the U.S. alone in 2014. So, what to do? Here are some options: If you really want to recycle gift cards after using them and have a way of collecting a big volume, they can be recycled by a company named Terracycle, which specializes in recycling materials that normally aren't recyclable. The company charges $91 to recycle a "small" box (25 x 25 x 46 centimetres) full of plastic cards. Some Canadian municipalities — for example, Strathcona in Alberta and Niagara Region in Ontario — allow people to drop off spent gift cards at certain depots for recycling. (The Municipality of Strathcona uses Terracycle as its gift card recycler.) Whatever you choose to do, think about what the gift card or certificate can be used to buy — the environmental impact of that purchase is probably much bigger than that of the card itself. — Emily Chung