Pulmonary diffusing capacity (lung transfer factor for carbon monoxide) has been assessed by the single breath (TLCOSB) and steady state (TLCOSS) techniques in well matched 90 females, 31 non-smoker and 29 smoker males, 18-50 years of age. Both TLCOSB and TLCOSS are significantly lower in females compared to non-smoker males (P < 0.001). Tobacco smoking statistically significantly reduces TLCOS...