Hair turns gray when melanocytes, color-producing cells located in hair follicles, stop producing color pigment. The result is colorless, transparent hair that appears gray or white to the human eye. All hair, regardless of color, picks up environmental contaminants and pollutants. While the contaminants are not visible on colored hair, they show up as a yellowish buildup on gray and white hair. The contaminants coat the hair shaft and must be removed through a deep-clarifying treatment. Fortunately, several household items will do the trick.

Mix equal parts of 3 percent hydrogen peroxide and water in a spray bottle. Spray clean, damp, non-conditioned hair liberally with the mixture. Comb through the hair with a wide-toothed comb or pick. Leave on for 15 to 20 minutes before rinsing. Repeat once a week to prevent buildup. In extreme cases, the solution can be left on longer; however, it will lighten colored hair if left on too long. Do not leave on longer than the recommended time if your hair is not 100 percent white or gray.

Work full-strength vinegar through clean, damp hair. Comb through to distribute the vinegar throughout, and wait for 15 minutes. Rinse, shampoo and condition the hair to remove the vinegar smell. Repeat once a week to keep hair free of buildup. On a side note, vinegar is great for removing hairspray and product buildup as well.

If you do not wish to use vinegar, you can substitute lemon juice. Follow the same instructions as those listed for vinegar. However, do not use lemon juice as a stripping agent every week if you still possess some hair color. Lemon juice can lighten hair over time. If you still have some hair color, alternate lemon juice with other home remedies listed here to maintain your natural color.

Since smoking is a major cause of hair yellowing, you should cover your hair while smoking. If possible, smoke outdoors. If not, create a smoking cap out of a piece of fabric and a large rubber band or strip of elastic connected at the edges to form a circle. Lay the fabric over the rubber band or elastic, fold the fabric around it, and staple or sew into place. Wear the cap every time you smoke to prevent smoke and nicotine from settling on your hair.