Resealing a macadam driveway is a smart way to protect a pricey investment, but be sure to ask your resealer to use only coal tar-free sealants. Coal tar is a common ingredient found in many asphalt seal coating products. The bad news? It’s also a suspected carcinogen. If you are resealing your driveway, do two things: Keep your windows closed during the resealing and for at least one week after a fresh application, and keep shoes off inside your house. Better yet, use sealers that are coal tar-free; DIYers will be glad to know that stores like The Home Depot and Lowe’s have banned coal tar completely from all of their asphalt sealing products.