Tread lightly without tripping up

Here are answers to everyday environmental questions that will leave you running short of excuses.

Q: Can CDs be recycled?
A: No. CDs are made from polycarbonate and acrylic plastics and have a reflective layer of aluminium. They also generally come with a label. This is a complex mix to break apart and recycle. If you're using CDs for storing data, you might want to consider DVD disks instead. While DVDs are made from the same materials, they hold almost seven times the data. Another good idea is to make sure you use re-writable discs. Instead of throwing out music CDs, you could swap with your friends, sell them at garage sales or to a broker, or donate them to charity.

Q: In a public toilet, is it better to dry your hands with the warm-air dryers or use paper towels?
A: Surprisingly, the hand dryer comes out as the better of the two choices. The electricity expended in 45 seconds of electric hand drying causes about 30 grams of carbon dioxide (CO2 - a greenhouse gas) to be released into the environment. The carbon dioxide produced in making two sheets of paper towel ranges from 45 grams (for paper on a roll) to 170 grams (for folded sheets). You can halve these figures by flicking your hands and then using half the paper or drying time.

Q: Is it OK to keep your computer on all day, or should you switch it off when not in use?
A: A standard desktop computer and monitor burn about the same electricity as a 100-watt light bulb. It might not sound much, but over a year that's about one tonne of CO2. Back in the 1980, we were told not to keep turning our computers on and off because it put stress on the hard drive. All big computer manufacturers now recommend that you turn off your machine when you're not using it. Today some manufacturers test-run their hard drives to cope with 40,000 on/off cycles - that's equivalent to switching your machine on and off 30 times every working day for five years. And if you're doing that in the office, you should really be rethinking your work practices!