Fig. 2

Changes in ΔF _CO, \( \dot{V}_{\text{CO}} ,\) \( \dot{V}_{{{\text{O}}_{ 2} }} , \) \( \dot{V}_{\text{E}} \) against time and the relationship between \( \dot{V}_{{{\text{O}}_{ 2} }} \) and \( \dot{V}_{\text{CO}} ,\) and between \( \dot{V}_{\text{E}} \) and \( \dot{V}_{\text{CO}} \) in one smoker (S-1). Note that ΔF _CO, \( \dot{V}_{\text{CO}} ,\) and the slope coefficients and intercepts of the regression equation between \( \dot{V}_{{{\text{O}}_{ 2} }} \) and \( \dot{V}_{\text{CO}} ,\) and between \( \dot{V}_{\text{E}} \) and \( \dot{V}_{\text{CO}} \) are higher compared with those in non-smokers