a.) Chemical emission rates for 12 different e-cigarettes (Goniewicz et. al., 2013). Data
for propylene glycol from 3 different e-cigarettes (Schripp et. al., 2012). Nicotine
calculated from propylene glycol emission rates assuming a concentration of 24 mg/ml
of nicotine in propylene glycol.
b.) NNK, 4-(n-nitrosomethylamino)-1-(3-pyridyl)1-butanone