Zoox Grounds Atlanta Test Fleet After Workers' Gas Exposure

Zoox has grounded its entire autonomous vehicle test fleet in Atlanta after as many as 40 workers were possibly exposed to carbon monoxide, carbon dioxide, or hydrogen sulfide inside its test vehicles last month, according to an OSHA letter viewed by TechCrunch.

The Amazon-owned company disputes that count. In a September 10 letter to the Occupational Safety and Health Administration, Zoox said it identified 28 employees who rode in six test vehicles that had an "unexplained odor." Ten of those workers "voluntarily underwent medical evaluation," and the company received only "one medical report identifying CO2 exposure." OSHA has since closed its inquiry.

The safety drivers, technically employed through third-party contractor HireArt, first reported exposure symptoms and strange smells in early August. On August 14, four workers riding together in one SUV — a configuration Zoox uses during training — fell ill mid-shift.

"Everything was fine. We was all laughing and talking, you know, just having a normal workday, and then everybody got quiet for some reason," Jay Davis, one of the contractors who got sick that day, told TechCrunch. After the crew stopped at a Chick-fil-A, one co-worker started vomiting and the others felt lightheaded.

Davis said Zoox put the group back on the road in a different test vehicle that same day. After driving all afternoon, he started vomiting at a food court after a few bites. He and two other workers went to the emergency room, where doctors told them their symptoms were consistent with carbon monoxide poisoning, though Davis's own test showed no elevated levels. Zoox later ordered the four workers to take what it described as a random drug test.

"They made us go right back in the field after we said we were throwing up," Davis said. "I emailed HR, told her what's going on, and I told her I feel like it's messed up that y'all made us go [back out]."

Davis filed the complaint with OSHA. The agency opened an inquiry and directed Zoox to investigate.

Workers continued reporting symptoms through most of August. On August 22, someone called 911 for a sick worker at the depot. The northwest Atlanta facility has operated at limited capacity since then, with test vehicles quarantined, according to two employees. Zoox's purpose-built electric robotaxis are not affected.

In its letter to OSHA, Zoox said it tested the vehicles' exhaust systems for leaks, performed a "smoke test" for cabin intrusions, and replaced all 12-volt batteries — damaged batteries can produce hydrogen sulfide, which carries a "rotten egg" smell some workers reported. The company told TechCrunch it has detected no battery damage and no signs of hydrogen sulfide, and that the only gas found in the affected vehicles was CO2. Zoox said it will add CO2 monitors that can also detect carbon monoxide and hydrogen sulfide.

"The safety and well-being of our Zoox test fleet operators is our primary concern in this situation," the company said in a statement. "While we investigate these reports thoroughly, we have ceased operations of our test vehicles in this market."

Zoox is an outlier among major robotaxi developers: its test fleet runs on internal combustion engines. Waymo, Tesla, Avride, and Motional all test with electric vehicles, which produce no exhaust gases. Zoox modifies Toyota Highlander SUVs with sensors, an autonomy computer, and an interior "snorkel" above the infotainment screen that pushes air toward rear-seat passengers. The company says it does not touch the ventilation systems, but vehicle modifications can create sealing issues — a risk the National Highway Traffic Safety Administration highlighted in its six-year investigation of carbon monoxide buildup in Ford Explorer SUVs, where the highest levels were found in modified police vehicles.

Zoox keeps its test vehicles running through much of the day to maintain sensor calibration and reduce boot time for the self-driving computer, and uses an exhaust-capture system at its indoor depots. The Atlanta incident lands as the company pushes into new cities and expands in Las Vegas and San Francisco in its bid to catch Waymo — a rapid growth phase during which contractors have previously reported injuries from sudden braking and swerving, and Waymo has reported similar test driver injuries to OSHA. Whether the CO2 monitors restore confidence among the contractor workforce will shape how quickly the Atlanta operation returns to full capacity.