Hypoxaemia and risk of asphyxia during underground work in artisanal cobalt mines.

This article investigates oxygen saturation (SpO₂) levels during underground work among artisanal cobalt miners in the southern Democratic Republic of the Congo (DRC), where over half of the cobalt for electric vehicle batteries is sourced. Using pulse oximetry on 86 underground and 24 surface miners at four time points, the study found that 35% of underground miners experienced hypoxaemia (SpO₂ <93%) during work, with 10% showing severe desaturation (SpO₂ <80%), while surface miners maintained stable oxygen levels. Measurements confirmed that ambient oxygen concentrations in several underground pits fell below the normal 21%, indicating insufficient mine ventilation as the likely cause of hypoxaemia and associated risks such as asphyxia. The findings highlight the need for technical interventions to improve ventilation and prevent acute and chronic health hazards in artisanal mining environments without stigmatizing the sector.