Impact of local and regional sources of PAHs on tribal reservation air quality in the U.S. Pacific Northwest.

Atmospheric fine particulate matter (PM2.5) transports polycyclic aromatic hydrocarbons (PAHs) regionally and globally, influencing the air quality of communities around the planet. Concentrations of 130 PAHs extracted from PM2.5, collected on a Native American Tribal Reservation in the Northern Puget Sound region of the American Pacific Northwest, were used to assess the air quality impacts of regional and local PAH sources, atmospheric transport, and human health implications. Wind coming from the southeast of the sampling locations increased the overall PAH concentration of the PM2.5, while winds from the southwest decreased the PAH concentration. Concentrations of PAH subclasses increased or decreased independently at the two sampling locations with different changes in wind patterns, changing the excess lifetime cancer risk significantly. No long-range transport was measured, but emissions from local and regional PAH sources were measured. Samples collected during regional wildfires showed increased PAH concentrations. Samples collected during predicted weather inversions resulted in the highest PAH concentrations, and up to a ten-fold increase in excess lifetime cancer risk over the normal days.

A Case Study Describing a Community-Engaged Approach for Evaluating Polycyclic Aromatic Hydrocarbon Exposure in a Native American Community.

In 2015, the Swinomish Indian Tribal Community (SITC) was impacted by an air toxic release from one of two nearby oil refineries. This experience motivated SITC members to learn more about their exposure to air toxics. On the invitation of SITC, this community-based study measured personal exposure to polycyclic aromatic hydrocarbons (PAHs) and conducted interviews with the volunteers to evaluate perceptions of the data and experience of participating. Non-smoking SITC members were recruited in March 2016 (N = 10) and January 2017 (N = 22) with seven volunteers participating both times. Volunteers wore a wristband passive sampler for 7 days and completed daily activity diaries. Wristbands were analyzed for 62 PAHs using gas chromatography mass spectrometry. Wilcoxon exact tests determined if the sum total PAHs (ΣPAH) differed by activity, proximity to the refineries, and time. Aggregated results were shared during community meetings, and volunteers received individual reports. Volunteers (N = 9) participated in individual interviews. All volunteers were exposed to different amounts and types of PAHs. Burning candles or using a wood stove and/or propane heating were associated with higher ΣPAH exposures. While ΣPAH was similar in both sampling periods, the composition of PAHs differed. More priority listed PAHs were detected in January (N = 17) versus March (N = 10). Among volunteers who participated in both sampling events, exposure to four PAHs significantly differed between seasons. Overall, volunteers reported that the study made them more aware of air pollution sources in their community. They also commented that the chemical nomenclature was difficult to understand, but appreciated the individual reports that allowed them to visually compare their data to the distribution of data collected in their community. For volunteers with lower exposures, these comparisons gave them relief. However, volunteers with higher exposures reported concern and several changed their behaviors to reduce their exposure to known PAH sources. This study provided an opportunity for SITC members to learn about their personal exposure to a class of air toxics within the context of their community. While the limitations of the study hindered the ability to identify sources of air toxics in the community, this activity appeared to raise awareness about ambient and indoor air pollution among the volunteers.