Paraffin candles are made with paraffin, a white waxy substance that is a bi-product of fuel. When burned and in liquid form, it emits soot and carcinogens, such as carbon monoxide, into the air. Since this is airborne, you, your loved ones and your pets can breathe these substances into your lungs. The gray-black residue that is left behind is known as "ghosting" and can be seen in excess on the tops of candles, curtains, walls, and in your air filters. High levels of these toxins have been known to cause illness in some who frequently burn paraffin-based candles. Symptoms can include headache, dizziness and nausea. Those with pet birds or reptiles should be extremely cautious burning paraffin candles since these animals are very sensitive to pollution.
Over the past few years, the soy candle has grown in popularity and for good reason. Soy candles do not contain any of the toxins or soot that paraffin candles release. This means you can burn your candles without the worry of ghosting on your curtains and walls, or clogging up your air filters. You can also breathe a sigh of relief knowing that you and your family are enjoying cleaner air that isn't polluted with carcinogens. Some allergy sufferers find that soy candles are less irritating than paraffin candles because of the absence of soot and toxins. Soy candles are easy on the environment, not only do they not emit toxins, but they are a renewable source! Unused paraffin wax is not biodegradable, but soy candle wax burns clean. You can even use the jar for other purposes after you've cleaned it. Here's some more good news, soy wax can actually hold more fragrance than paraffin wax, so you get a strong fragrance throughout the life of the candle. You can also enjoy your candle much longer because soy wax burns at only 127 degrees fahrenheit, which is a much lower temperature than paraffin candles.
So to sum up: soy candles burn longer and cleaner than paraffin. Why would you burn anything but soy?