Commercial air fresheners contain harmful chemicals like phthalates, which cause birth defects and reproductive problems, according to the Natural Resource Defense Council. Making an air freshener at home allows a pleasant-smelling home without the chemicals. Not only do homemade air fresheners avoid putting harmful chemicals in the home, but you have more options. Essential oils come in dozens of scents. Mix and match scents to create a one-of-a-kind fragrance. For example, add orange and cinnamon together for a spicy, fall scent.