Zoox halts Atlanta robotaxi testing after safety drivers report toxic gas exposure

Atlanta test fleet grounded

Zoox has pulled its autonomous vehicle test fleet off Atlanta roads after safety drivers reported symptoms consistent with toxic gas exposure inside the company's modified SUVs last month, TechCrunch reports. The grounding followed a complaint filed with the Occupational Safety and Health Administration by one of the affected workers; the regulator opened an inquiry, directed Zoox to investigate, and has since closed it.

According to an OSHA letter viewed by TechCrunch, as many as 40 workers may have been exposed. Zoox, which Amazon owns, puts the figure lower: in a September 10 letter to the regulator, the company said it identified 28 employees who rode in six test vehicles that had an "unexplained odor," 10 of whom chose to undergo medical evaluation. Only one medical report identified CO2 exposure, the company said.

The affected vehicles are modified Toyota Highlander SUVs. Zoox's purpose-built, all-electric robotaxis are not affected.

A rough August

Symptoms and strange smells were reported through much of August. Jay Davis, the contractor who filed the OSHA complaint, told TechCrunch that on August 14 he and three colleagues were riding together in a test SUV — a setup Zoox uses while training new employees — when the mood in the car suddenly changed and one worker asked whether anyone else was "feeling weird." At their 10 a.m. break, one of the group began vomiting and the others felt lightheaded.

Davis said Zoox had the SUV towed back to its Atlanta depot but then assigned the same group to a different test vehicle for the rest of the day. They felt sick again that afternoon, and Davis vomited after a few bites of a meal at a food court. "They made us go right back in the field after we said we were throwing up," he told TechCrunch, adding that he raised the issue with HR. Zoox's test drivers are technically employed through HireArt, a third-party contractor.

Reports continued until August 22, when someone called 911 for a sick worker. Two employees told TechCrunch the northwest Atlanta facility has since run at limited capacity, with the test vehicles quarantined.

The culprit remains unclear

Exactly what the workers were exposed to is unresolved. Emergency room staff told Davis and two colleagues that their symptoms were consistent with carbon monoxide exposure, and the OSHA complaint mentions possible carbon dioxide exposure. Zoox told TechCrunch it has not found carbon monoxide — which is odorless — in its vehicles, consulted an outside medical expert, and detected only CO2.

Some workers noticed a rotten-egg smell, which can point to hydrogen sulfide from damaged 12-volt batteries. Zoox removed and replaced all of the batteries but did not tell OSHA whether it found any damage, according to TechCrunch. The company also tested the SUVs' exhaust systems for leaks and ran a smoke test for cabin intrusions, without saying whether either check turned anything up. Zoox plans to add CO2 monitors to the vehicles.

A combustion-engine outlier

Zoox is unusual among major robotaxi developers in that its test fleet runs on internal combustion. Waymo, Tesla, Avride and Motional all test with electric vehicles, which produce no exhaust; May Mobility uses some hybrid vans and Nvidia uses a small number of gas and electric Mercedes-Benz sedans, TechCrunch notes.

That matters because burning fuel produces carbon monoxide and carbon dioxide, which can enter a cabin through exhaust leaks or build up when a vehicle runs in an enclosed space. Zoox keeps its test vehicles running for much of the day to keep sensors calibrated and shorten the boot time of the self-driving computer, and it uses exhaust-capture systems at indoor depots similar to those used for fire trucks. The company modifies Highlanders with sensors, an autonomy computer and an interior air snorkel, though it says it leaves the ventilation system untouched. Vehicle modifications of any kind can compromise cabin seals: the National Highway Traffic Safety Administration's six-year investigation into carbon monoxide in Ford Explorers found the highest gas levels in modified police vehicles fitted with sirens and lights.

Why it matters

The incident lands as Zoox pushes into new cities and grows operations in Las Vegas and San Francisco to chase market leader Waymo — expansion that has already taken a toll on test workers, who have previously reported injuries from sudden braking and swerving; similar injuries have been reported to OSHA by Waymo as well. It is a reminder that the human cost of developing autonomy is borne largely by contractors rather than riders, and that an industry pivoting to electric robotaxis still relies on gasoline-powered cars behind the scenes. Zoox said in a statement that its operators' safety is its primary concern and that it has ceased test vehicle operations in Atlanta while it investigates. The company gave no timeline for the fleet's return.