Moss Biomonitoring and Isotopic Signatures Reveal Aviation Fuel as Local Lead Source near Oregon Airports

This article, “Moss Biomonitoring and Isotopic Signatures Reveal Aviation Fuel as Local Lead Source near Oregon Airports”  found higher concentrations of lead in proximity to the Hillsboro and Troutdale Airports. 

Here is a link to the article in Nature Communications Sustainability (open access): https://www.nature.com/articles/s44458-026-00130-x

Here is a link on the study, background information, and resources: https://ehsc.oregonstate.edu/our-research/research-highlights/leaded-aviation-gas

Below are a few excerpts. 

“The lower maximum lead concentration for Troutdale moss (5.50 mg/kg), compared to Hillsboro moss (21.60 mg/kg), aligns with NEI emissions data, indicating that Troutdale Airport’s lead emissions are about half those of the higher-traffic Hillsboro Airport31.”

“The six sites closest to the most active runway at Hillsboro Airport, within 0.5–0.7 km, had the highest lead concentrations in the study, ranging from 7.08 to 21.6 mg/kg (Figs. 2, 3a), with a median concentration of 15.3 mg/kg. These values are up to 6.67× higher than the Portland background and 46.7× higher than the NW Oregon rural moss concentration (0.463 mg/kg)24.”

“Lead emissions from piston-engine aircraft using leaded aviation gasoline (avgas) remain a significant source of environmental contamination near regional airports, posing potential health risks to nearby communities. Passive biomonitoring using the epiphytic moss Orthotrichum lyellii was combined with lead isotope fingerprinting to quantify lead concentrations and distinguish between legacy leaded gasoline and current avgas emissions near Hillsboro and Troutdale airports in Oregon. Here we show that lead levels are elevated by up to 50 times the rural background near airports, with isotopic signatures confirming avgas as a dominant local source. These findings indicate that avgas use contributes substantially to environmental lead burdens in adjacent residential neighborhoods. Moss biomonitoring offers a cost-effective approach for detecting and mapping lead pollution from airport emissions, supporting efforts to evaluate exposure risks and inform regulatory actions aimed at reducing lead exposure from aviation sources”

“The objective of this study was to determine the impact of leaded aviation fuel (avgas) use at the Hillsboro and Troutdale regional airports in the Portland metropolitan area of northwest Oregon (USA) on environmental lead levels, using the epiphytic moss Orthotrichum lyellii. Both airports are among the top three lead emitters in Oregon. In 2017, Hillsboro Airport ranked #10 among U.S. airports for annual lead emissions, producing 550 kg lead31,47,48,49, while Troutdale Airport ranked #88 nationally, with 251 kg, about 45% of Hillsboro’s emissions31. This study used the 2017 National Emissions Inventory (NEI) data, rather than the most recent (2020) data, to avoid potential misrepresentation caused by pandemic-related reductions in air traffic50,51. We hypothesize that elevated lead concentrations and distinct isotope ratios from moss samples collected near the Hillsboro and Troutdale airports will trace leaded aviation fuel emissions, distinguishing them from other urban sources. Moreover, lead emissions from these airports pose a greater potential exposure risk than those in rural areas, as both are adjacent to residential areas, including schools, daycares, and parks, with 2020 census tract population densities ranging from 2764.5 to 12,522.6 people per square mile52. In this study, we present findings that show elevated lead concentrations near regional airports in northwest Oregon, with lead isotope analysis confirming airport contributions.”

“Detection of lead from avgas in residential neighborhoods near these regional airports demonstrates that the continued use of leaded gasoline is contributing to local lead pollution. Lead is persistent in the environment and a critical air pollutant with significant public health concerns. Even after the adoption of unleaded aviation fuel alternatives in general aviation, elevated environmental lead levels are expected to persist due to long-term accumulation in local soils. This study demonstrates the potential use of moss as a low-cost, reliable screening method for lead emissions near major sources. Studies of moss and other biomonitors near additional regional airports may help to determine national variability in the environmental impact of these sources, inform the development of child protection zones around regional airports, and assess the impact of new regulations reducing or banning the use of leaded avgas.”