Sorption kinetics and equilibria of nicotine with polypropylene carpet were quantified at 0, 50, and 90% relative humidity (RH) and in the presence of 0-, 20-, and 40-ppm NH3. Nicotine was introduced into a 10-liter, carpet-covered, stainless steel chamber by flash evaporating of 50-?l pure liquid nicotine and then equilibrating of surface sorption for 30 min prior to outlet gas sampling. The chamber was controlled at an air exchange rate of 1.2 h-1. A XAD-4 resin tube was used to collect gas-phase nicotine and then desorbed and analyzed with a gas chromatography-mass spectrometer (GC/MS). Kinetic sorption parameters were determined by fitting a mass balance model to experimental results using a non linear regression. Results show that an equilibrium partition coefficient, ke, of nicotine tended to increase as the RH increased. In the presence of 20- and 40-ppm NH3, the values of ke decreased by 14-40% at 50 and 90% RH, but the effect of NH3 was not observed at 0% RH.