Zoox Grounds Atlanta Test Fleet After Toxic Gas Exposures Make Workers Ill

Zoox, the Amazon-owned autonomous vehicle developer, has suspended operations of its test fleet in Atlanta after repeated incidents in which workers were exposed to potentially harmful gases inside modified vehicles, resulting in illness and prompting a federal workplace safety investigation. As many as 40 employees may have been affected over several weeks in August, with contractors reporting dizziness, nausea, vomiting, and lingering uncertainty about what made them sick. The crisis has raised urgent questions about fleet design, maintenance protocols, and whether rapid expansion in pursuit of market share is outpacing safety oversight.

The Incidents: Symptoms, Smells, and Being Sent Back to Work

The first signs of trouble emerged in early August, when test drivers began reporting unusual odours and physical symptoms, lightheadedness, headaches, and fatigue, while riding in the Toyota Highlander SUVs used for development. On August 14, the situation escalated dramatically. Four contractors, including Jay Davis, who later filed a complaint with the Occupational Safety and Health Administration (OSHA), were training together in one vehicle when they suddenly fell quiet. “Everybody got quiet for some reason,” Davis recalled. By their morning stop, one colleague was vomiting; all felt unwell.

Instead of being sent home or placed on light duty, the group was reportedly assigned to a second vehicle and told to resume testing. Later that day, Davis fell ill again while eating and was taken to the emergency room alongside two others. Medical staff told them their symptoms were consistent with carbon monoxide exposure, though tests did not detect elevated levels in their systems. Complaints and sickness continued through the month until August 22, when a worker became severely unwell and someone at the facility called 911. The Atlanta site has operated at limited capacity ever since, with vehicles quarantined.

Davis was blunt about the experience: “They made us go right back in the field after we said we were throwing up.” He emailed human resources to protest, but the pattern of reporting illness and being returned to duty left him feeling unheard and unsafe.

What Gas? Conflicting Findings and Uncertain Causes

OSHA opened an inquiry following Davis’s complaint, which listed potential exposure to carbon monoxide, carbon dioxide, and hydrogen sulfide. The picture remains incomplete:

• Zoox’s investigation: The company told OSHA it found carbon dioxide in affected vehicles but no carbon monoxide. It replaced 12-volt batteries which can release hydrogen sulfide when damaged, producing a distinct “rotten egg” odour and tested exhaust systems and cabin integrity. Employees reported smelling that exact odour, yet Zoox later stated it detected no battery damage and no hydrogen sulfide.

• Medical evidence: Ten workers sought evaluation; one report cited CO₂ exposure. Emergency room staff noted symptoms consistent with carbon monoxide but did not confirm elevated levels in patients.

• Vehicle design: Unlike competitors Waymo, Tesla, and Motional which use all-electric fleets Zoox relies on gasoline-powered SUVs for testing. These vehicles produce exhaust gases that can enter the cabin through leaks or poor ventilation. Modifications to accommodate sensors, computers, and custom airflow “snorkels” may further compromise sealing, a pattern seen in other cases, including NHTSA’s long-running investigation into Ford Explorers, where added equipment created gaps that allowed carbon monoxide buildup.

Zoox stated it does not alter base ventilation systems, but the company’s unique reliance on internal combustion engines sets it apart in the industry and introduces risks others do not face.

Response and Reforms

Zoox has paused testing in Atlanta while investigations continue. The company committed to installing multi-gas monitors capable of detecting carbon monoxide, carbon dioxide, and hydrogen sulfide across the fleet. OSHA has since closed its inquiry, though the broader questions remain unresolved. Zoox maintained: “The safety and well-being of our Zoox test fleet operators is our primary concern… We are taking ongoing, appropriate, and cautious actions.”

Critics, however, point to a pattern of pressure. The Atlanta expansion is part of a broader push to grow quickly and narrow the gap with leader Waymo. Reports from Waymo also note rising injuries sprains, pain, whiplash linked to sudden braking and manoeuvring, filed with OSHA in recent months. As the sector scales, the human cost of testing is becoming increasingly visible.

Growth at What Cost?

The events in Atlanta are more than a local incident they are a warning. Autonomous vehicle technology promises to save lives and transform cities, but the people building it are facing preventable risks on the job. Gas exposure, unclear causes, delayed action, and pressure to keep working despite illness speak to a culture where speed may have overridden safety. For Zoox, the path forward requires full transparency, independent verification of root causes, and genuine accountability to the workers who put themselves in harm’s way every day.

As Jay Davis and his colleagues know firsthand, progress should never come at the expense of the people making it possible.