Dr. Robert Boutelle is a particle scientist who has authored procedures for working with lead nano materials.  On August 31, 2024, Dr. Boutelle gave a talk about the health impacts of lead in aviation fuel.   Piston engine aircraft, like those using Boulder Airport, burn this fuel.   

In 2022, Boulder Airport sold $110,000 worth of leaded aviation fuel.   This contained 488.4 pounds of lead.   On burning, 95% of the lead in aviation fuel is emitted in the form of dust nanoparticles.

A May 2024 Colorado Department of Public Health and the Environment study shows that proximity to an airport has a statistically significant effect on blood lead levels of children.  It says, "results suggest the potential impact on children’s blood lead levels is greatest at distance less than 2 miles from an airport location.”   This talk provide images showing homes, schools, and daycares located within this radius of Boulder Airport.  

Other highlights from the talk: 

• The link between children’s blood lead levels and proximity to airports is clearly established
• There are three risk factors from exposure:
  • duration of exposure,  
  • amount of the toxin to create an impact, and  
  • bodily response 
• Lead from avgas exposure is bad across all three risk factors:  
  • the exposure is continuous,  
  • only a tiny amount causes a negative impact,  
  • it is particularly absorbable by the body and difficult to detoxify 
• Even tiny amounts of lead can permanently impact a child’s ability, potential and future  earnings 
• The risk from an airport can be comparable to and at times worse than the Flint Water Crisis
• Children’s blood lead levels correlate with both fuel sales and proximity to an airport 
• Many Boulder city and county residents live within two miles of Boulder Airport 
• There are schools and childcare centers within two miles of Boulder Airport 
• Due to the constant exposure and tiny particle size, it is very difficult to mitigate for lead emitted from avgas  
• Leaded aviation fuel will not be gone in 2030
• HEPA filters can filter for COVID, but not lead particles from avgas

Authorities 

Dr. Boutelle is a scientist of nanoparticles, including lead. He wrote operating procedures for using lead nano materials. 

Another leading authority on lead is Dr. Sammy Zahran, also from Colorado, who has produced many studies on lead exposure in children, including the Flint Water Crisis (FWC). Dr. Zahran is an author of the Reid-Hillview study (RHS), which directly correlated airport activity with children’s blood lead levels. This is peer reviewed, public research, vetted by other scientists, editors, and scientific reviewers who are experts in their fields. Dr. Zahran showed that for children within 1.5 miles of Reid-Hillview airport, the lead exposure was just as bad or worse than the FWC. 

Background 

In October 2023 the EPA announced an Endangerment Finding stating that there is a correlation between avgas fuel sales and airport activity with blood lead levels. The EAP Director said the science is clear - lead exposure can cause irreversible and lifelong health effects in children. The dominant source of lead emissions in our air today is from aircraft that use leaded fuel. 

In Colorado, the 2017 EPA emissions inventory shows that aircraft emissions cause 72% of lead emissions in our environment, more than all other sources of lead from industry combined. 

A graphic plot of the 2017 National Emissions Inventory shows hotspots of lead emissions at our airports. In 2017 Boulder had 284 pounds of lead emissions, and Erie had 526 pounds (left side of slide). Today (right side) Boulder shows 488 pounds while Erie went down to 223 pounds. 

The piston engine planes, propeller aircraft, at Boulder Airport (BDU) use leaded fuel. Once the lead is emitted, it must go into the environment. 

Toxicity factors 

There are three main factors to lead toxicity: 

• Frequency/duration of contact 
• Amount of exposure 
• The body’s response - how readily the toxin penetrates and how the body detoxifies 

Frequency of contact 

The body is more apt to detoxify from a single, acute exposure. With constant, long term exposure, the body does not have the chance to detoxify and the toxin builds up in the body over time. 

Touch and go activity burns the most fuel and thus creates the most lead emissions by constantly taking off and landing. Take off requires thrust to generate lift, requiring more fuel. In this cycle, 80% of the lead emissions occur during takeoff. This is why airports emit two orders of magnitude more lead than anywhere else in the vicinity. 

There is still exposure from overflights, because the lead falls to the ground, where it collects.

Measuring lead in the environment 

In Superior [near Rocky Mountain Metropolitan Airport], each of 9 homes took dust samples in 2 locations and 18/18 samples contained lead. These homes did not have lead paint or pipes. Therefore, the lead came from outside.

UPDATE 09.15.24: The testing method used was Inductively Coupled Plasma Mass Spectroscopy, ICP-MS. See https://en.wikipedia.org/wiki/Inductively_coupled_plasma_mass_spectrometry. 

The EPA standard for lead on surfaces is 10 micrograms per square foot. There is a proposal to change this to 3 micrograms. 

In Centennial, residents tested parks under the touch and go patterns using wipe samples on surfaces where children might play, including swings, slides, benches, and climbing structures. Samples were sent to a lab for testing. Nearly every surface was higher than 10 micrograms per square foot. 

This demonstrates that we are constantly exposed to lead emissions that build up in our bodies. 

Amount of Exposure 

Lead exposure in adults is not as well studied as in children. Higher levels of lead have been shown to cause hypertension and heart effects, possibly dementia. Long term exposure in adults has not been studied. 

Many studies have focused on children. Lead is particularly pernicious for children because their neuronal pathways are developing while they are trying to learn and grow. Lead inhibits the calcium pathways of the neurons forever. 

Even tiny quantities can cause lower IQ, decreased ability to pay attention, and underperformance in school. These are permanent effects, causing societal impacts, including lower earning of pay, lower scores on tests, and negative impact in college admissions. 

One clear study showed the impact. When Nascar banned leaded fuel at their racetracks [in 2007], children raised near the racetracks performed substantially better than earlier cohorts. 

One study showed a societal cost of $71,000 per child. 

Pregnant mother’s exposure has strong effects on a child's IQ. 

By the time you can detect lead in children’s blood it is already too late. 

The body’s response to lead 

Lead is a heavy metal. It is difficult for the body to detoxify from lead. 

How well the toxin penetrates the body depends on its form. With lead, the particle size determines how easily it can bypass body defenses and enter the bloodstream. Particles 18 nanometers in size and smaller can easily penetrate body cells. 

Avgas particles are around 13 nanometers is size, a perfect size to penetrate mucosal barriers. Simply breathing is exposure. Coughing and sneezing do not defend. 

This is a much smaller size than particles from automotive fuel (now banned). So while automotive lead has been removed from our environment, avgas lead is far more toxic because it is so readily absorbed. 

Exposure with respect to fuel sales 

The RHS showed children’s blood lead levels correlate with the amount of fuel sold at the airport. 

Exposure with respect to airport proximity 

Both the RHS and the Colorado Department of Public Health (CDPHE) study showed that children’s blood lead levels varied with the distance to the airport. 

The CDPHE studied that area around 12 airports in Colorado. At each one they saw increased blood lead levels as children were closer to the airport. 

The CDPHE study says, “Consistent with previous studies, our analysis finds a small but significant increase in mean blood levels and the odds of exceeding CDC reference levels among children who live near airports, servicing general aviation aircraft in Colorado. And results suggest the potential impact on children’s blood lead levels is greatest at distance less than 2 miles from an airport.” 

Wind is a factor in the the distribution of emitted lead. Downwind exposure is the worst. CDPHE study shows being downwind for just 21 out of 60 days causes much higher exposure. 

This shows that the worst exposure occurs within two miles of the airport and downwind.

Exposure from Boulder Airport 

This wind rose diagram shows average predominate wind directions and speed in Boulder over the last 14 years, coming mostly from the south west and north. Thus, the greatest downwind is north east [into County jurisdiction] and also south. 

The following images show distances .5 and 2 miles from Boulder airport, including schools and daycare centers.

Mitigation, what can be done? 

Here are three steps to toxin mitigation, in order of effectiveness: 

1. Get rid of the toxin by eliminating the source 
2. Reduce the amount in circulation 
3. Personal protective equipment, PPE 

Eliminate the source 

Removing lead from airports is not on the horizon. We can only ask that unleaded fuel be used. 

The FAA requires airports to offer leaded fuel through 2030. 

New infrastructure is required for unleaded fuel. [This is a huge failure to date - literally nothing has been done toward solving this problem, even though lead was removed from auto fuel 30 years ago.] 

There is a fuel now that can be used by any general aviation aircraft, GAMI, but it is not yet certified due to liability concerns. 

Another fuel, 94UL, can be used by 66% of current aircraft. It requires owners to pay for a certification, $200 to $1,500 per aircraft, depending upon horsepower. And, the unleaded fuel costs more. Sometimes pilots mix this with leaded fuel to get higher octane levels. 

These barriers taken together show how difficult it is to move to unleaded fuel. One fuel candidate dropped out saying, “The FAA requirements are making this impossible.” 

Reduce the exposure 

The Town of Superior has asked Rocky Mountain Metropolitan Airport to ban touch and go activity. Airport sponsors can ban certain activities for safety reasons. [The situation is pending.] 

Airport sponsors could institute landing fees, to decrease touch and go activity. 

The FAA is reflexively opposed to these measures and resists them. Semantic arguments around safety must be made. 

Mitigation through personal behaviors 

It’s hard to reduce exposure when lead is so prevalent. HEPA filters will not filter for particles this small. 

Suggestions: 

• Get a blood test to see where you stand.
• If you affected or thinking about starting a family, you may want to move.
• Dust with a wet rather than a dry cloth.
• Keep doors and windows closed, don’t go outside during high activity periods. 
• Avoid eating food from your gardens because plants can absorb heavy metals from the soil.
• Remove shoes inside to prevent tracking lead indoors. 
• Keep soil covered with grass, bark, or gravel to prevent dust. 
• Wash hands often, especially before eating and sleeping. 

The choice of blood testing lab matters. It needs to be sensitive to at least 2 micrograms per deciliter. For research purposes, scientists will use labs that go to a much higher precision. 

Questions and answers 

~~~~~ 

Question: Regarding measuring lead in the body, how representative is a blood test? 

Answer: The body tries to keep a homeostatic state where elements (?) are balanced across the body. So lead will be in blood, tissue, bones, etc. If one area gets lower, lead will leach out of another area. With constant exposure, blood lead levels tend to be pretty constant. 

Note that the RHS AND CDPHE studies saw higher levels in the summer, presumably due to greater flying activity and greater fuel consumption, coupled with people being outdoors. It takes more fuel to fly in hot weather. 

~~~~~ 

Question: what is ANCA? Where does FAA rule end and local jurisdiction take over? 

Answer: the Airport Noise and Capacity Act. In the 1990’s, airport sponsors were limiting activity, creating curfews, etc. The FAA did not like this. It instituted the ANCA in the 1990’s to keep airport sponsors from restricting airport activity except for “safety” reasons. 

ANCA usually applies to jets, but it does not apply to general aviation. [BDU only supports general, or private, aviation.] So, the handcuffs binding GA airport sponsors is not so much a jurisdictional issue, but rather grant obligations incurred when a sponsor takes FAA funding. 

Sponsors do have control over rental rates and landing fees.

In the Superior case, the homeowners sued for inverse condemnation, which the Federal Court upheld.

~~~~~ 

Question: Airport supporters say their lead testing shows there is no lead. 

Answer: They tested air quality for lead in a deeply flawed manner. The Superior homeowner dust tests and the Centennial tests used a far more sensitive method called inductive mass spectroscopy. The tests you cite used flame absorption spectroscopy, which is extremely insensitive. It can’t even detect the new EPA soil regulations of 80 micrograms per gram. So, their tests in no way negates the finds of the RHS or the CDPHE study. 

UPDATE 09.15.24: The Town of Superior used Flame Atomic Absorption Spectroscopy testing, FAAS. See https://en.wikipedia.org/wiki/Atomic_absorption_spectroscopy. 

Also, Superior did an air test that used a filter that was 300 nanometers in diameter. That's equivalent to throwing a baseball through a net 15 feet wide and hoping to catch it. So also heavily flawed. 

I recommend you use a firm that does inductively coupled mass spectroscopy to get the most sensitive and most accurate information. 

~~~~~

Question: Is it worth testing the soil? 

Answer: Soil testing is like looking for a needle in a haystack. There may be ways to reduce the search, but overall it is impractical. 

~~~~~ 

Question: Is it worth using a HEPA filter? 

Answer: The best HEPA filters go down to 100 nm, which filters out COVID but not 13 nm avgas lead particles. 

~~~~~ 

Question: why aren’t they simply required to prove that this is safe? 

Answer: The FAA Reauthorization Act has hard mechanisms to prevent the prohibition of leaded fuel. It may require fines of $5,000/day if leaded fuel is withdrawn from an airport. But there may be wiggle room through pursuing certain angles and semantics.

~~~~~ 

Question: Do you know any airport that has been able to ban touch and go activity? 

Answer: Torrence, CA, banned touch and goes around January of 2024. I don’t know where that stands now. 

~~~~~ 

Question: Who has jurisdiction? The EPA or the FAA? 

Answer: That is being played out. The EPA wants health on the ground and the FAA wants safety in the skies for pilots. The EPA’s endangerment finding was their first step. It’s a very slow process. I think they are now in a two year period of discussion. 

~~~~~ 

Question: Once lead is in the soil, how can it be remediated? 

Answer: Good question. What metric do you use? EPA’s soil metric? Or, do you just say, it’s already too much? Lead doesn’t go away. It can blow around. It can go into the water supply. It will stick around until it’s removed. So, the EPA may say it’s fine, but your blood lead levels may be up. 

Could remediate by putting a layer on top of it or removing a layer of soil. But if planes continue to fly, it will be redeposited. 

~~~~~ 

Question: How can lead get from soil into our body? Is going barefoot bad? 

Answer: Plants can absorb lead from the soil, and you can take it in by eating it. If dust is kicked up, you can breath it. 

~~~~~ 

Question: Are you aware of property values around an airport being impacted by lead? 

Answer: Yes. Houses with lead paint will have a lower value than those without. In California property owners are required to disclose if the property is in the vicinity of an airport. 

~~~~~ 

Question: If a Colorado property owner has knowledge of lead on their property, say from a windowsill test and not due to paint, are they required to disclose that to potential buyer? That would be awkward, and could keep people from testing. If you were a homeowner you’d have to make that difficult decision.

Answer: Definitely. That’s why in my presentations I never disclose whose homes were involved in testing. There may be naturally occurring lead in your environment. If you looked for lead outside and found it, would you have to disclose it? I don’t know the answer. 

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Question: Can you talk about the process of remediation and what makes it safe? For example, Stapleton Airport is now a large housing complex. What made it safe? 

Answer: I imagine it would involve what happened after the Marshall fires and what was also done at Rocky Flats for plutonium. The top layer of soil was removed, probably 8 to 12 inches, and new soil was put on top. Afterwards the government says, just don’t dig too deeply and you’ll be fine. 

References 

Clearing the Skies: Unveiling the Health Impacts of Leaded Aviation Fuel

Leaded aviation gasoline exposure risk and child blood lead levels 

The association between childhood blood lead levels and proximity to airports in Colorado How NASCAR’s switch to unleaded gas boosted test scores near racetracks 

Nascar shows danger of airborne lead during pregnancy 

The association between lead exposure and crime: A systematic review 

What are U.S. standards for lead levels?

Exposures to Lead and Other Metals at an Aircraft and Flight School Facility