"We consistently put [detectors] by the operator on their seat and that's to be representative of their exposures," said Marissa Baker, a UW assistant professor of environmental and occupational health sciences who co-led the assessment.
Researchers additionally hid the battery-powered monitoring devices behind signs and panels. Same with trains.
The study analyzed 28 evenings between March and June of this year. Researchers collected samples from 11 buses and 19 train cars.
Out of the 78 air samples, researchers found fentanyl in a quarter of them. 100% of those air samples had methamphetamine. Out of the 102 surface samples, almost half had detectable fentanyl. 98% of those air samples had methamphetamine.
Researchers said, however, that just because it's there, it doesn't mean it's at a level that would harm anyone.
"Even the folks that do these drugs recreationally are not taking it with the goal of overdosing," Baker said. "It would be very unlikely that there would be enough to generate it secondhand that could cause an overdose to anybody."
Researchers said, regardless of the exposure level transit operators have, it's important to draw attention to the stress this can cause for an employee who has to see it at their workplace, which can take a toll mentally.
This year alone, almost 500 people have died this year from methamphetamine overdose in King County. More than 700 people have died from a fentanyl overdose. That's more than this point last year.
This study did not test any transit operators or passengers to see if they had secondhand fentanyl or methamphetamine in their systems. The times, trains and buses were specifically chosen by the transit agencies because operators has reported seeing drug use on those lines.
Sound Transit said to help its staff, it's creating a mentorship program for workers. They also a 24/7 phone line workers can call for support.