Ozone interactions with human hair: ozone uptake rates and product formation

In laboratory experiments we quantify the ozone uptake rate for human hair and the resulting formation of volatile aldehydes and ketones. Hair samples were exposed to ozone in a tubular Teflon reactor. The integrated ozone uptake was quantified by measuring the inlet and outlet ozone concentration over a 24 hour period. Volatile reaction products were identified and quantified by sampling the reactor inlet and outlet using Tenax sorption tubes followed by thermal desorption and GCMS analysis. Volatile reaction products consistently observed in all experiments include geranyl acetone and 6methyl 5-hepten 2-one. These are products of the ozone – squalene reaction. Compounds formed as a result of ozone chemistry with personal care products have yet to be identified. On average, the integrated ozone uptake for the washed hair samples was 1.12×10 mol O3 g and for unwashed hair was 1.87 ×10 mol O3 g. For a hair sample that was not washed for 3 days ozone uptake was about ten times higher than the average for all other hair samples. Further the yield of geranyl acetone, 6 methyl 5-hepten-2-one and decanal was consistently higher on unwashed hair. While natural oils that coat hair contribute to ozone reactions on unwashed hair, ozone appears to be reacting with other, unidentified compounds on washed hair.