New data shows that Tesla workers at the Fremont factory in California spent almost three times more days off the job due to work-related injuries and illness in 2018 compared to the year before, showcasing the strain they were under during the company’s push to produce more electric cars.

Taking into account Tesla’s growth in headcount, the amount of time per factory employee has doubled last year.

Bloomberg released those figures after it got hold of Tesla’s report to the Occupational Safety and Health Administration (OSHA), which also included an overall rate of injuries per hour of work that’s roughly similar to that of 2017.

The company’s factory workers lost 22,454 days in 2018, up from 7,619 in 2017. This translates into an average time missed of 66 work days per employee, compared to 35 in 2017.

Deborah Berkowitz, who worked for OSHA as chief of staff under President Obama, called the data “alarming” and a “red flag”.

Tesla however thinks otherwise, claiming there’s no correlation between the number of days its employees were out of work and the severity of injuries. The company managed to boost its production output while keeping injuries roughly in proportion with the increase in total hours worked, said Laurie Shelby, Tesla’s VP for environmental health and safety.

“The most important metric is fatalities, and our number is zero,” Shelby commented. “It was a big ramp year for Model 3, so there were a lot more hours worked, more production staff and more potential for incidents. We really focused on making sure we had our safety team out in the area as we ramped.”