This Recommended Method is applicable to the estimation of human smoke exposure to nicotine and NFDPM (nicotine-free dry particulate matter, also known as tar) using linear calibration regression equations between mainstream smoke yields and corresponding analytes from part-filter extracts. The method is referred to as the Part-Filter Method (PFM). The cigarettes under investigation must contain a cellulose acetate filter element at the mouthend. The method has been successfully applied to population of smokers smoking cigarettes between 1 and 15 mg ISO NFDPM yields as determined by ISO 4387.