Scientists at the University of Colorado spent 1.5 years studying the air quality of 6 different nail salons in Colorado state. They measured the concentration levels of formaldehyde as well as benzene, toluene, ethylbenzene, and xylene. It was found that in all 6 nail salons, the concentration level of these toxic elements was many times higher than normal which increases the risk of developing nasopharynx cancer, leukemia, and other types of cancer.