September 2023 – University of Washington School of Public Health: Assessing fentanyl and methamphetamine in the air and on surfaces of transit vehicles
Executive Summary
UW researchers undertook an exposure assessment for fentanyl and methamphetamine on transit vehicles. Researchers collected air and surface samples for fentanyl and methamphetamine from a total of 11 buses and 19 train cars. Samples were collected over 28 nights between March 27 and June 22, 2023. Agency partners identified routes, runs, and time of day when smoking of these controlled substances would be most likely to occur based on agency-provided data. Air and surface samples were collected at or near the operator, and in other areas throughout the vehicle where smoke would be expected to accumulate.
UW researchers analyzed the findings from 78 air samples and 102 surface samples collected from the transit vehicles. Of the 78 air samples, 20 (25%) had detectable fentanyl and 100% had detectable methamphetamine. Of the 102 surface samples, 47 (46%) had detectable fentanyl and 100 (98%) had detectable methamphetamine. Detection of fentanyl or methamphetamine by the lab does not mean it poses a health risk to operators or the riding public.
No enforceable state or federal regulations exist for methamphetamine or fentanyl exposures occurring in a workplace setting. However, related occupational safety and health standards that are not substance-specific could apply to drug smoke, residues, or paraphernalia found in a workplace setting. These may include standards requiring an accident prevention program, hazard communication, personal protective equipment (PPE), and others.
One of the 78 air samples collected exceeded the Environmental Protection Agency (EPA) occupational exposure guideline for fentanyl in the air (0.1 micrograms fentanyl per cubic meter of air, µg/m3). This is the level of fentanyl measured in air that workplaces should strive to stay below in order to ensure worker health and safety, but it is not an enforceable regulation. No similar state or federal occupational guideline exists for airborne methamphetamine.
Two of the 102 surface samples exceeded the Washington State Department of Health decontamination guideline established for methamphetamine (15 nanograms of methamphetamine per square centimeter, ng/cm2). This is a health-based standard, therefore cleaning surfaces to be below this level should protect both operator and rider health.
In general, levels of methamphetamine and fentanyl found on transit vehicles in this exposure assessment are unlikely to cause acute, short-term physical health effects for the riding public who spend less time on transit than the operators. At the levels seen in this study, there is no evidence of acute medical conditions resulting from passive exposure to fentanyl or methamphetamine (such as from touching contaminated surfaces or inhaling secondhand smoke).
The potential for long-term physical or mental health effects related to low-level, daily secondhand exposure to fentanyl and methamphetamine should also be considered for transit operators, who spend 40+ hours each week on the bus or train. Long-term health effects related to daily secondhand exposure to these substances are not established. In the absence of data relating the amount of these substances found in the air or on surfaces to human health outcomes, protective measures are prudent to keep operators safe. UW researchers recommend using protective measures to reduce exposure to these substances to the lowest level that is reasonably achievable.
Protective measures may help to reduce exposure to fentanyl and methamphetamine on transit for operators and the riding public. Suggested protective measures include improved ventilation and air filtration, enhanced cleaning practices, and operator training on agency protocols around the use of drugs on vehicles and other related topics. These controls should be evaluated to determine effectiveness. It is also recommended that agencies continue to work with state and county health agencies to address the use of controlled substances on transit. Enhanced cleaning and filtration have additional benefits for public health such as reducing exposure to wildfire smoke and reducing the spread of respiratory illness.
Observing drug use in a bus or train can be stress-inducing for operators and the riding public, and may increase feelings of stress, anxiety, or job dissatisfaction. For individuals who may be in recovery or have had family or loved ones impacted by drug use, these feelings may be particularly heightened. These mental and psychological impacts should also be acknowledged and considered.
Results from this exposure assessment could inform ongoing research focused on occupational exposure to secondhand smoke from drug use. This research can help establish best practices for transit agencies in Washington State, the Pacific Northwest, and nationally. Additional research is needed to establish the long- and short-term health effects related to inhaling or touching secondhand fentanyl or methamphetamine.
What this assessment did not do:
This assessment did not characterize short- or long-term health outcomes associated with secondhand exposure to fentanyl or methamphetamine. This assessment did not collect internal biomarkers of exposure (such as urine or blood) from operators or the riding public to understand how much of what was found in the air or on surfaces entered people’s bodies.
This assessment did not comprehensively characterize every bus or train route across all times of day. While our results reflect actual and feasible exposures for transit operators, results presented here cannot be assumed to be typical for all transit lines, particularly for those on which reported drug use is less frequent.
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