The general work ability of a person, from a physiological point of view, is the ability of an organism to convert energy, i.e. to transform the chemical energy of the nutrients into mechanical energy or work. It is only part of a professional work ability that involves adapting different human abilities to specific job requirements, occupations, and environmental conditions in that workplace. Spirometry is one of the diagnostic methods for assessing work ability, since there are many occupations that require greater oxygen demand due to greater physical effort or a specific working environment (divers, firefighters, miners). In the assessment we use static and dynamic functions such as: pulmonary volumes and capacities, flow-volumes loops, forced expiratory volumes, diffuse lung capacity for carbon monoxide and data from submaximal exercise tests. The methods and parameters used in the assessment of pulmonary function are described further below, but in assessing the work ability, we need to take account of health and physical and psychological abilities of the workers, as well as the working conditions, requirements and working environment. It is necessary to establish a more precise diagnosis of the workers health and to provide a more precise assessment of their biological characteristics and psycho-physical capabilities, as well as to analyze the psychophysical demands of work and the working environment.