Introduction Since 2013 in Chile a specific occupational evaluation, determined by Ministry of Health, is required to work in high altitude (defined as 3000 to 5500 metres above sea level). The aim of this study was to describe the results of health evaluation for high-altitude work in a Chilean copper mine during year 2016.

Methods Health evaluations performed during 2016 in Andina Division of Codelco, the Chilean Public Mining Company, were analysed. All medical contraindications for high- altitude work were checked and classified into categories. Time to recover medical aptitude for work was calculated.

Results From 1542 workers exposed to high altitude work, 1483 underwent medical evaluation according to Chilean regulation during 2016. This evaluation included: medical history, modified Lake-Louise questionnaire, EKG, chest X-rays and blood tests (haemoglobin, plasmatic creatinine, lipid panel and glucose level). 29 workers (1.96% of all evaluated) had a permanent contraindication for working at high altitude: 15 of them due to cardiologic conditions (ischaemic heart disease mainly); 6 of them due to unstable diabetes mellitus; 3 of them had respiratory diseases (COPD) and the other 5 had other specific conditions (chronic liver disease, stroke with motor impairment, refractory epilepsy, severe psychiatric disorder and polycithemia vera). These workers were relocated in middle or low-altitude positions. 167 workers (11.26% of all evaluated) had a temporary contraindication for high-altitude work. The average duration of the working restriction was 11 days until the condition was treated. 143 (86%) were cardiovascular and metabolic conditions: high blood pressure, hyperglycemia, severe obesity and dyslipidemia. 13 workers (0.88%) had high levels of haemoglobin and underwent specific additional exams to find secondary causes. Only 2 of them were diagnosed as Occupational Polycythemia, which is one of the three high-altitude related occupational diseases recognised by Chilean law.

Discussion High-altitude Occupational Polycythemia prevalence was 0.1% in our Company, which is lower than other series. This might be explained because of the type of work-shifts that allow workers to sleep everyday under 1000 metres above sea level. Cardiovascular and metabolic conditions were the most frequent causes of contraindication to work, which is explained by the high prevalence of chronic diseases and cardiovascular risk factors in Chilean population.