# Zoox halts Atlanta AV tests after toxic gas exposure incidents Safety drivers reported carbon monoxide-like symptoms in modified test SUVs, prompting OSHA investigation - **Source:** [TechCrunch](https://techcrunch.com) - **Published:** 2026-09-23 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/e9690afc-78b8-4f3f-bdbe-4d2724ff73eb ## Test fleet grounded Zoox suspended its autonomous vehicle testing operations in Atlanta after multiple safety drivers reported symptoms consistent with toxic gas exposure. The incidents occurred in modified Toyota Highlander SUVs used for testing, with workers experiencing nausea, vomiting, and lightheadedness. At least 28 employees across six vehicles reported unexplained odors. The company quarantined affected vehicles and limited facility operations while investigating potential carbon monoxide, carbon dioxide, or hydrogen sulfide exposure. ## OSHA complaint filed A contractor filed a formal complaint with OSHA after being required to continue working despite experiencing symptoms. Workers reported being put back into different vehicles that may have also contained toxic gases. OSHA opened an inquiry and received documentation showing Zoox examined vehicles for CO2, replaced 12-volt batteries (potential hydrogen sulfide sources), and implemented medical evaluations. The agency has since closed its investigation after Zoox agreed to install CO2 monitors in test vehicles. ## Modified test vehicles Zoox's test fleet differs from competitors by using gasoline-powered SUVs rather than electric vehicles. The company modifies Highlanders with autonomous driving sensors and computers, including adding an interior 'snorkel' for airflow. While Zoox claims not to alter ventilation systems, any modifications can create sealing issues. This contrasts with Waymo, Tesla, and Motional's all-electric fleets. Ford's 6-year NHTSA investigation into Explorer CO leaks showed how vehicle modifications can exacerbate gas intrusion risks. ## August incident timeline The most severe exposure occurred on August 14 when four workers shared an SUV during training. After experiencing symptoms at a Chick-fil-A stop, they were given another vehicle and told to continue working. Later that day, one worker vomited in a food court. Three visited an ER where symptoms were deemed consistent with CO poisoning, though tests showed no elevated levels. On August 22, another severe case prompted a 911 call. Workers reported symptoms throughout August until operations were limited. ## Battery replacement Zoox identified damaged 12-volt batteries as a potential hydrogen sulfide source, replacing all units in the test fleet. Hydrogen sulfide produces a distinctive rotten egg smell that multiple workers reported detecting. The company performed smoke tests to check for cabin intrusions and examined exhaust systems for leaks, though findings weren't disclosed. Zoox maintains vehicles run continuously for sensor calibration, increasing exposure risks if gases enter the cabin. ## Contractor treatment Affected workers are employed through third-party contractor HireArt, complicating medical response and accountability. One worker reported being given a workers' compensation hotline and Poison Control number rather than immediate medical attention. Zoox later required drug tests for symptomatic employees. The company stated operator safety is its primary concern but faced criticism for initially continuing operations after exposure reports. ## Industry context The incidents occurred as Zoox expands testing to new cities to compete with Waymo. This rapid growth has raised safety concerns, following previous reports of injuries from sudden braking in test vehicles. Both Zoox and Waymo have reported test driver injuries to OSHA. The Atlanta situation highlights unique risks of Zoox's combustion-engine fleet compared to competitors' electric vehicles, which don't produce exhaust gases that could leak into cabins. ## Exhaust management Zoox uses industrial-grade exhaust capture systems at indoor depots, similar to firehouse truck fume solutions, to mitigate gas buildup. However, these protections don't address potential leaks during road operations. The company keeps test vehicles running continuously to reduce computer boot times, creating extended exposure windows if gases enter the cabin. This operational requirement may conflict with safety protocols when gas exposure risks emerge. ## Regulatory implications The incidents reveal gaps in safety protocols for autonomous vehicle testing with modified combustion engines. While NHTSA has investigated conventional vehicles for CO leaks, AV test fleets present new challenges. Zoox's response—adding CO2 monitors and medical evaluations—may set precedents for the industry. The situation underscores how traditional automotive risks persist even in cutting-edge AV development programs, requiring hybrid safety approaches. ## Sources covering this story - https://techcrunch.com/2026/09/23/zoox-grounds-atlanta-test-fleet-after-workers-report-toxic-gas-exposure-symptoms/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._