Objectives: Nicotine is a natural alkaloid and insecticide in tobacco leaves. Green tobacco sickness (GTS) is known as a disease of acute nicotine intoxication among tobacco farmers. Until now, GTS has been recognized globally as a disease that results from nicotine absorption through the skin. However, we assumed that GTS might also result from nicotine inhalation as well as absorption. We aimed to measure the airborne nicotine concentrations in various work environments of Korean tobacco farmers. Methods: We measured the nicotine concentrations in the tobacco fields, private curing barns, and joint curing barns of farmers from July to October 2010. All sampling and analyses of airborne nicotine were conducted according to the National Institute for Occupational Safety and Health manual of analytic methods. Results: The airborne nicotine concentrations (geometric mean [geometric standard deviation]) in the tobacco field were $83.4mg/m^3$ (1.2) in the upper region and $93.3mg/m^3$(1.2) in the lower region. In addition, the nicotine concentration by personal sampling was $150.1mg/m^3$. Similarly, the nicotine concentrations in the private curing barn, workers in curing barns, the front yard of the curing barn, and in the joint curing barn were $323.7mg/m^3$(2.0), $121.0mg/m^3$(1.5), $73.7mg/m^3$(1.7), and $610.3mg/m^3$(1.0), respectively. Conclusions: The nicotine concentration in the workplaces of tobacco farmers was very high. Future studies should measure the environmental concentration of nicotine that is inhaled by tobacco farmers.