Background: Silicosis is known in industrial workers for centuries. Till recently, the mainstay of its diagnosis and progress was clinical examination of the respiratory system, pulmonary function test and chest radiography. Several biomarkers such as serum angiotensin converting enzyme (ACE) activity have been examined to determine the extent of silicosis.

Objective: To elucidate the effect of age, gender, duration of exposure to silica dust, smoking habit, and pulmonary function status on the serum ACE activity among quartz stone workers without disease.

Methods: A cross-sectional study was carried out on 134 (111 men and 14 women) workers of quartz stone crushing units were studied. Standard diagnostic criteria were used for diagnosing silicosis and tuberculosis. Pulmonary functions of the participants were also assessed.

Results: The mean±SD age for participants was 26.1±6.3 years (26.6±6.3 for men and 21.9±4.3 for women). The mean±SD duration of exposure was 1.1±1.9 years. In the present study, only one case of silicosis and eight cases of tuberculosis were found. The mean±SD serum ACE levels for those with and without respiratory disease were 68.44±11.61, and 66.9±14.4 IU/L, respectively (p>0.05).

Conclusion: We could not observe any association between serum ACE activity and age, gender, duration of exposure, smoking habits and pulmonary function status. However, elevated levels of serum ACE was found in a solitary case of silicosis.