Since 2019, this Nairobi office block has been the epicenter of Facebook’s content moderation operation for the whole of Sub-Saharan Africa. Its remit includes Ethiopia, where Facebook is trying to prevent content on its platform contributing to incitement to violence in an escalating civil war.

Despite their importance to Facebook, the workers in this Nairobi office are among the lowest-paid workers for the platform anywhere in the world, with some of them taking home as little as $1.50 per hour, a TIME investigation found. The testimonies of Sama employees reveal a workplace culture characterized by mental trauma, intimidation, and alleged suppression of the right to unionize. The revelations raise serious questions about whether Facebook—which periodically sends its own employees to Nairobi to monitor Sama’s operations—is exploiting the very people upon whom it is depending to ensure its platform is safe in Ethiopia and across the continent. And just as Facebook needs them most, TIME can reveal that content moderators at Sama are leaving the company in droves due to poor pay and working conditions, with six Ethiopians resigning in a single week in January.