Lead Pollution in Portland Neighborhoods

Miki Barnes
August 14, 2024

"... we want to be conscious of what we're putting into the environment because it may be with us for a long time. We see that with the leaded gasoline. Any metals, like lead, that we're putting into the environment, the amount that's going to be there is also cumulative. So, if you're just putting a little in from one source and a little in from another, that's adding up."

–Alyssa Shiel Associate Professor in the College of Earth, Ocean and Atmospheric Sciences at Oregon State University, Lead Author on the Portland Lead Moss Study

A 7/23/2024 Oregon State University Newsroom release, Study of Urban Moss Raises Concerns About Lead Levels in Older Portland Neighborhoods, explained that "moss growing on trees in urban areas is an effective air monitoring system because it has a wide surface area to collect contaminants that settle out of the air around it."

For the purposes of the study, urban moss samples gathered in Portland in 2013 were compared to samples obtained in 2017 from nearby rural locations. The lead author Alyssa Shiel and co-authors Sarah Jovan, and Christina Murphy, found that "Lead levels in moss are as much as 600 times higher in older Portland neighborhoods where lead-sheathed telecommunications cables were once used compared to lead levels in nearby rural areas..." In addition, "The findings showed nearly 12 times higher lead levels in urban Portland than found in rural areas nearby. Chemical analysis indicates that much of the lead in the environment is due to leaded gasoline, which continues to persist in the environment nearly three decades after it was banned in the United States."

Per Shiel, "The lead introduced into the environment by leaded gas just hasn't gone away. We have to live with it."

The study, Lead-Sheathed Telecom Cables and Historic Leaded Gasoline Emissions Substantially Raise Environmental Lead Levels in Portland, Oregon, published in Nature Communications Earth & Environment found "leaded gasoline to be a pervasive and persistent lead source, decades after the complete phase out of leaded gasoline use by on-road vehicles. The highest lead levels, up to 590× the rural background, are found in older residential neighborhoods where relic lead-sheathed telecommunication cables were identified. Leaching of lead from these cables is thought to be responsible for elevated lead in older residential neighborhoods in cities across the country."

The study also found that "The lead isotopic compositions of moss from Portland sites (excluding those with lead cables) are consistent with that of leaded gasoline used in Portland (this study) and California...This suggests that the resuspension of soil and dust contaminated with lead from the historical use of leaded gasoline is the dominant lead source for most Portland mosses."

The study described lead as "a highly toxic metal associated with adverse health effects including hypertension and cardiovascular disease, renal disease, neurodegenerative diseases like ALS, and decreased neurobehavioral-cognitive function. Children are especially vulnerable as even low levels of lead in blood can adversely impact neurodevelopment and cause lower IQ, poorer academic achievement, cognitive deficits, behavioral problems, and delayed puberty. According to the Centers for Disease Control and Prevention (CDC) Advisory Committee on Childhood Lead Poisoning Prevention, no exposure limits are widely agreed upon as safe. Consequently, there is significant interest in identifying sources of lead pollution so that health risks can be mitigated."

To access a 7/23/2024 Oregon Public Broadcasting Think Out Loud interview OSU Study Raises Concerns About Elevated Lead Levels from Old Telephone Cables with Alyssa Shiel click here.

Oregon Aviation Watch applauds the OSU study and appreciates the well-deserved media attention it has received. However, it is important to recognize that pollution from leaded gasoline is not only historical. It continues to be emitted on a daily basis by general aviation aircraft that still burn leaded gasoline. The screenshots included in this posting are examples of how lead is emitted into the skies over Portland every single day and night.

Aviation Lead Emissions Routinely Deposited Over Portland

Please take the time to view the flight tracks in this section as they show how lead is released and distributed over Portland and the surrounding area on a daily basis. The screenshots included in this posting were gathered during a two-week period between 7/30/2024 and 8/13/2024. They represent but a small sampling of the aircraft that are continuing to emit lead over the greater Portland Metropolitan area.

Lead in automotive fuel was banned more than 25 years ago. However, piston-engine aircraft continue to emit lead over Portland and the surrounding community. Ironically, the aircraft delivering the most concentrated lead applications are registered to the City of Portland, the Portland Police Bureau, Multnomah County Sheriff's Office and Clackamas County Sheriff's Office. Flight students and private pilots also contribute to the lead and pollution footprint.

Background on Aviation Lead Pollution

In the U.S. there are approximately 170,000 piston-engine aircraft still using leaded avgas. According to the Environmental Protection Agency (EPA), these aircraft are responsible for 70% of all airborne lead emissions in the U.S. In Oregon, the percentage of lead released by mobile aircraft is even higher, 87%, compared to all other sectors.

Piston-engine aircraft which includes smaller airplanes and helicopters used for flight training, recreational flying, private pilots and police surveillance, release approximately one million pounds, close to 500 tons, of lead into the atmosphere every single year. Commercial and private jets by contrast, use a kerosene-based fuel that does not contain lead.

City of Portland Surveillance Aircraft - N425EJ

The flight track below, generated by a single aircraft, N425EJ, had been in the air, releasing lead, noise, and other pollutants, for more than 3 hours when the screenshot below was captured on Sunday, 8/11/2024 ay 7:10 PM. While in flight, it circled repeatedly over various neighborhoods in North, NE, and SE Portland.

 

N425EJ had been engaging in aerial surveillance over Portland and Clackamas County for more than 3 hours when the screenshot below was captured on Sunday, 08/04/2024 at 8:30 PM.

 

This next screenshot is a close-up of the flight track discussed above. It shows N425EJ circling over the Montavilla, Parkrose, Hazelwood, Madison and surrounding communities approximately 30 times during a one-to-two-hour period all the while releasing lead, noise and other toxins into the environment. In addition, it flew multiple times over neighborhoods in Hawthorne, Ladd's Edition, Buckman and other SE locations.

 

The next screenshot of N425EJ was captured at 12:37 PM on Sunday, 8/4/2024. The aircraft departed from PDX on 8/03/2024 at 10:32 PM. It had been emitting lead, noise and other toxins over parts of NE and SE Portland for more than 2 hours at the time this photo was taken.

 

The screenshot below was captured on Friday, 8/2/2024 at 9:42 PM. N425EJ had been releasing lead, noise, and other pollutants over North, NE and SE Portland for more than 3 hours at the time this photo was taken.

 

The screenshot below shows N425EJ, circling over older Portland neighborhoods in North, Northeast, and Southeast Portland neighborhoods. It had been releasing lead, noise and other pollutants into the air for more than 2 hours when this screenshot was captured at 1:12 AM on Saturday, 8/03/2024.

 

Portland Police Bureau Surveillance Aircraft - N2163J

The Portland Police Bureau aerial surveillance flight shown below had been emitting lead over Portland neighborhoods for 3-4 hours when this screenshot was captured at 10:40 PM on Tuesday, 8/14/2024. The flight track included 40 revolutions over Montavilla and Madison neighborhoods and another 40 over neighborhoods around the Centennial Community Association in outer SE Portland.

 

This screenshot below, produced by N2163J, registered to the Portland Police Bureau. was captured on Wednesday, 8/7/2024 at 4:45 PM after the aircraft had spent hours releasing lead, noise and other toxins over numerous Portland neighborhoods as well as parts of Clackamas County.

 

Below is a detail from the above 8/7/2024 screenshot showing the aircraft flying multiple times over Cully, Irvington, Laurelhurst, Rockwood, Montavilla, Mt. Tabor, and surrounding neighborhoods.

 

The flight track below was also produced by N2163J. It was captured on Tuesday 8/6/2024 at 10:58 PM after the aircraft had spent hours releasing lead, noise and other toxins while circling over North, NE and SE Portland neighborhoods.

 

The screenshot below, produced by N2163J was captured at 8:18 PM on 7/30/2024. The image shows that the aircraft circled and looped repetitively over various neighborhoods throughout the Portland area.

 

Clackamas County Sheriff's Office Surveillance Aircraft (N931EM)

This Clackamas County Sheriff's Office aircraft, N931EM, had been repetitively circling over SE Portland and parts of Clackamas County for several hours when this screenshot was captured on Thursday, 8/8/2024 at 9:16 PM.

 

In this next screenshot, N931EM had been circling repetitively over SE Portland and various Clackamas County locations for close to 3 hours when this image was captured on Saturday, 8/3/2024 at 11:47 PM.

 

Multnomah County Sheriff's Office – N910TW

This flight track over SE Portland, Gresham, Fairview, Troutdale, Wood Village and other neighborhoods was produced by an aircraft registered to the Multnomah County Sheriff's Office. The aircraft had been in the air for several hours when this screenshot was captured.

 

This Multnomah County Police Bureau Aircraft had circled multiple Portland neighborhoods for several hours when the screenshot below was captured on 8/3/2024 around 11:00 PM.

 

Closing Remarks

It's important to bear in mind that other piston engine aircraft including student, private, and recreational pilots are adding to the lead pollution burden borne by area residents. In addition, aviation noise is known to have adverse impacts on human health as do the PM2.5, benzene, and other carcinogenic toxins released by this mode of fossil fuel burning aircraft.

Specific to lead, it may be possible to differentiate between legacy lead from automotive fuel vs leaded aviation fuel emissions. To access a 9/11/2020 article in the Journal of Atmospheric Research by Jack Griffith, Electron Microscopic Characterization of Exhaust Particles Containing Lead Dibromide Beads Expelled from Aircraft Burning Leaded Gasoline, click here. The article's abstract states that lead particles emitted by aircraft are significantly smaller than those emitted by automobiles, and so are more readily absorbed by the human body: "Of significant concern, the smaller aircraft particles could penetrate mucosal barriers in the lung and be readily taken up by epithelial cells."

As stated in the introduction to the article, "studies have suggested that the reduction in IQ levels in children exposed to lead from aviation gasoline emissions may constitute a 1 billion dollar a year economic loss in the US" (Wolfe et al., 2016; Zahran et al., 2017).

Lead is a pernicious neurotoxin which is known to cause potentially irreversible damage. For this reason immediate steps need to be taken to drastically reduce piston-engine air traffic over the greater Portland Metro area.