The study population is three groups of male and female residents of City of Almaty, the largest city in Kazakhstan, with a population of 1,7 million people, containing 9% of the country's total population aged 33-59. The first group is current smokers with more than 10 pack-year history of smoking. The second group is individuals who quitted smoking from one to five years ago and have more than 10 pack-year history of smoking. The third group is persons who has never smoked regularly, i.e. smoked less than 100 cigarettes in his or her lifetime.