Researchers from the University of Washington unveiled their findings after transit workers in the Pacific Northwest complained earlier this year that they were being exposed to second-hand fentanyl and methamphetamine smoke.
Researchers from the university's Environmental and Occupational Health Sciences department revealed their findings Thursday showing that the overwhelming majority of air and surface samples had detectable traces of methamphetamine.
The researchers collected samples on 11 buses and 19 train cars on 28 nights from March 27 through June 22. With the help of transit authorities, the researchers took 78 air samples and 102 surface samples at times when smoking of these substances was considered high.
The study found that 25% of air samples and 46% of surface samples were positive for detectable levels of fentanyl. The researchers also found that 100% of the air samples tested positive for methamphetamine, and 98% of surface samples returned traces of the drug.
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In a call with reporters, researchers stressed that by and large, the levels detected were not high enough to prompt concern about significant near-term health effects.
"Just because we can measure it in the lab does not necessarily mean that it's at a level that poses a health risk to operators or riders. Labs can measure very small amounts of things," lead researcher Marissa Baker said. "I will also acknowledge that short and long-term health effects of secondhand exposure to these drugs are not well established. This is really a novel exposure in this context."
Baker said for the average rider, their concern should be minimal.
"I continue to feel safe on buses and trains, but as I mentioned, there are differences for operators than riders who will be on the train for much shorter periods of time," she said.
But that doesn't mean that drivers, or the public for that matter, remain comfortable on buses or trains where illicit drugs are being smoked.
"That doesn't mean that smelling smoke doesn't have effects, you know, we've all been exposed to smoke of all sorts of varieties and gotten a headache or a cough or mucous membrane irritation and things like that," said Dr. Robert Hendrickson, medical director of the Oregon Poison Center. "So I don't want to downplay that in any way. The ideal situation for everyone is that no one is exposed to secondhand smoke at all. But from the standpoint of fentanyl toxicity or methamphetamine toxicity, I feel very comfortable that that is not a risk based on the numbers in this study."
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Researchers recommended that mass transit operators enact more frequent deep cleanings of trains and buses. They also recommend training operators on protocols, real versus perceived risks and Narcan.
King County Metro, one of the transit authorities that first brought up concerns about drug use on mass transit, responded to Thursday's findings.
"We place a high value on being responsive to employee and rider concerns, and in making decisions based on science," said King County Metro General Manager Michelle Allison. "The study reaffirms our strategies are the right ones, and adds to Metro’s determination to continuously improve."
The transit authority said it will conduct deep cleaning of buses every 10-14 days and do daily wipe-downs of high-touch areas. It also plans on outfitting all buses with MERV-13 filters, which they say are capable of removing viruses and drug smoke particulates. They also are budgeted to hire more security officers.
