Answers: Besides women overdying their hair
Toxins and fluoride can effect problems with imbalancing their estrogen which affects things similar to their hair.
Supplements for clean hair are
vitamin C, zinc, selenium, PABA, pantothenic tart, biotin and choline.
also use a ph balanced shampoo.
Teasing, bleaching, pulling, corn-rows, etc etc, will hold a huge impact versus pollutants. I'd go beside hair assault before blaming dirty nouns. Look to the obvious.