Zoox has halted operations of its autonomous vehicle test fleet in Atlanta after multiple workers reported symptoms linked to exposure to toxic gases, including possible carbon monoxide, carbon dioxide, or hydrogen sulfide. These incidents occurred in August, with some employees experiencing acute symptoms such as vomiting and lightheadedness after riding in the modified gas-powered test SUVs. One worker filed a complaint with OSHA, prompting the agency to open an inquiry and instruct Zoox to investigate the situation. Although OSHA has since closed its inquiry, Zoox continues its investigation and has suspended testing in the Atlanta market as a precaution.

The affected vehicles are modified Toyota Highlanders with internal combustion engines, unlike the fully electric fleets used by competitors like Waymo and Tesla. Zoox’s modifications focus mainly on autonomy hardware and do not include ventilation system changes. However, workers reported strange odors, including a "rotten egg" smell consistent with hydrogen sulfide, possibly linked to damaged 12-volt batteries. Zoox tested for gas leaks and replaced batteries where needed but stated it has not found evidence of carbon monoxide within its vehicles. The company plans to install CO2 monitors capable of detecting other gases across its fleet moving forward.

Workers described feeling unwell during shifts, with some being directed back to testing in different vehicles even after showing symptoms, which raised safety concerns among employees and contractors. One incident even led someone at the depot to call 911 for a sick worker. Employees have voiced frustration over the handling of these exposures and the pressure to continue work despite feeling ill. The complaints come amid Zoox’s broader efforts to expand its autonomous operations in cities like Las Vegas and San Francisco to compete with market leaders.

This situation highlights the risks associated with using combustion engine vehicles for autonomous testing, an approach that differs significantly from competitors relying on electric vehicles that do not produce exhaust gases. Zoox employs an exhaust capture system at its indoor staging facilities to mitigate toxic gas buildup, but the recent incidents show challenges remain in ensuring operator safety. The company stresses that operator wellbeing is paramount and that it is taking thorough investigative and safety measures as it works to resume safe testing.