Chronic exposure of workers to powder containing crystalline silica (SiO2) can lead to chronic lung diseases (lung cancer, silicosis, etc.). The aim of the study was to evaluate the exposure of Greek construction workers to SiO2 and describe their pulmonary function. The study involved 86 outdoor and underground workers. Medical and professional history was obtained, and samples were collected for the determination of SiO2 levels. Pulmonary function tests, radiological examination and evaluation of radiographs were, also performed. During the examination of the pulmonary function, the majority of the workers were within normal range (61.4%) while the rest were diagnosed with mild (26.5%) and more severe impairment (7.2%). Working conditions (underground-outdoor) were statistically significantly related to the categorization of pulmonary function (P = 0.038). During radiological examination, the type of working conditions (underground-outdoor) were statistically significantly related to the categorization of these findings (P = 0.044). Of the 69 employees, 52 did not present findings (75.4%) and five (5) were diagnosed with findings specific to occupational diseases (7.2%). The environmental exposure to RCS (Respirable crystalline silica) was detected at 12 mg / m3 in the workplace, which is beyond the legal limits. Underground workers with more than 15 years of exposure to SiO2 may experience silicification in its chronic form compared to the workers of outdoor activities.