Buy beeswax candles
Conventional candles are made out of paraffin, a petroleum residue. Not only are these sourced and produced in an environmentally damaging way but when you burn them they degrade the indoor air quality. A better alternative are candles made from beeswax or natural vegetable-based wax. These are better for your health as well as biodegradable once you are done with them. There are also ways to re-use the wax and make more candles if you’re up for a quick tutorial on Youtube.