Dear Heloise: Dryer sheets are not biodegradable, so they're here forever. I stopped using them altogether in favor of wool dryer balls. It's a one-time purchase that lasts for many years and eliminates the cost of buying dryer sheets. It also gets rid of buildup on clothing, linens (especially towels that lose their absorbency), and laundry machines. I win all around, and so does the environment! Thanks for the years of good advice.