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Danger above: Threat of toxic lead in aviation gas

By Stacy Gittleman

The United States banned leaded gasoline beginning with cars made in 1975. During this time, the nascent Environmental Protection Agency (EPA), which had just been founded in 1970 under the Clean Air Act, ruled that leaded fuel posed health hazards for humans, especially in brain development of fetuses, infants and young children. The last gallon of leaded gasoline was pumped into the last car by January 1, 1996. As a result, there was a dramatic decrease in ambient lead levels nationwide.

Still, there remains a significant sector in the transportation industry that continues to use leaded fuel. And to find the culprits of the last emitters of leaded gasoline, all you have to do is look up.

Flying single piston engine airplanes (PEA), also known as general aircraft, is a popular hobby for flying enthusiasts. Not only that, but according to the Federal Aviation Administration (FAA), smaller planes are used for critical purposes, including business and personal travel, instructional flying, aerial surveys, agriculture, firefighting, law enforcement, medical emergencies and express freight.

The state’s busiest general aviation airport, and the 12th busiest airport of its kind in the world, is the Oakland County International Airport (OCIA) located on M-59 (Highland Road) in Waterford Township, resting on the shores of Pontiac Lake and immediately south of Williams Lake. On average, 120,000 takeoffs and landings occur at this county-owned and operated airport each year, with an average 390 flights per day as documented by the FAA in 2022. More than 150 corporations base their aircraft at OCIA, many with several aircraft. According to county data, 658 aircraft are based at the airport, including 325 single piston engine aircraft, 95 multi-engine aircraft and 18 helicopters.

Oakland County owns and operates two other airports – the Oakland/Troy Airport located between Maple Road and 14 Mile Road, between Coolidge Highway and Crooks Road, and the Oakland/Southwest Airport on Pontiac Trail in New Hudson.

According to research studies focused on the use of leaded gas in aviation, nationwide, there are 16 million people and three million children who live within a kilometer of the 19,000 airports that service the nation’s fleet of around 170,000 registered single piston aircraft, or PEAs. These small aircraft comprise about 70 percent of the nation’s air fleet. In 2011, these aircraft consumed an estimated 225 million gallons of a high-octane fuel called avgas, according to a 2013 study, which found that emissions into the environment at that time were about one million pounds of lead each year. The flow of lead from PEAs constitutes between half and two-thirds of remaining lead emissions in the United States, according to a 2008 EPA study.

While this amount is small compared to the amount of leaded fuel that old gas guzzlers used in decades past, and ambient lead levels have dropped off precipitously in the last several decades, the impact is spatially concentrated near the thousands of smaller general aircraft airports and airstrips that dot the nation.

Though there has been a push from environmental groups, researchers and public health officials to get the lead out of aviation fuel since the early 2000’s, as with other policies, regulations have not caught up with the mounting research. Aviation government authorities, organizations and pilots contend that until there is a safe fuel alternative that will not cause a risk of engine failure while in flight, the general aviation fleet continues to power itself with high-octane leaded fuel. Though the EPA, along with the Federal Aviation Agency, have pledged since 2010 to remove lead from avgas, an easy-to-produce, affordable and safe fuel that can be used across a range of PEAs has yet to come on the market.

Unlike the country’s fleet – 6,000 of them – of larger commercial jets, which use kerosene-based jet fuel, PEAs rely on a fuel formulated with Tetraethyl lead. It is added to avgas to increase octane and thereby prevent “knock,” or uncontrolled fuel detonation, which can damage aircraft engines and even cause sudden engine failure. Many aircraft engines have been designed to deliver a lot of power while weighing as little as possible, and they need high-octane fuels to do so. Today the most widely available avgas is 100-octane low lead, or 100LL, which would be equivalent to 105-octane automobile gasoline. This grade of avgas satisfies the requirements of all piston engines using avgas, regardless of their performance level.

Jet aircraft and turbine-powered, propeller aircraft do not use avgas, but instead use fuels very similar to kerosene, which does not contain a lead additive.

Nilton Renno is professor of climate and space sciences and engineering at the University of Michigan. When he is not busy with his award-winning research with NASA working on better rover technologies to explore the surface of Mars or instructing classes, he is a general aviation hobbyist pilot.

Renno began flying at the age of 14, first honing his skills in unmotorized gliders and then sailplanes when he was a researcher at the University of Arizona. He now clocks in a few flights per week in his single-engine Lear jet to destinations on the East Coast or Chicago out of Ann Arbor’s municipal airport.

As a pilot, Renno explained there is yet to exist a safe enough fuel to fly general aviation piston aircraft. Though aircraft designers are experimenting with new types of engines that do not require a high compression rate that demands leaded fuel, it is the older model engines – which have not changed much in the last 50 years – that have a better coolant high-compression rate and are more reliable in terms of safety.

“As of yet, there is no safe solution for a replacement to leaded gasoline in general aviation,” Renno asserted. “The reason this entire fleet of aircraft cannot choose a different fuel is those engines are air coolant dependent and have a high compression ratio. This means the temperature in the engine cylinder gets much hotter than a typical car. Because of this, if there is not the proper balance between air and fuel – there is a risk of an explosion. And premature explosions can cause great damage and danger to the engine. So that’s the basic reason we still need the leaded fuel for these types of aircraft.”

On the horizon, Renno said there are experimental aircraft engine designs in the works from European companies such as Diamond which feature twin engines akin to an automobile. But their heavier engines are a drawback for flight and the complexities of their engines make them less reliable than older engines.

Renno said that the FAA has been working for over a decade in pursuit of alternative fuels that do not contain lead and is “getting close.” The challenge is in the price point and the economic practicality of developing such a specialized fuel that will only be used by a tiny slice of any of the country’s fleet of aircraft.

“The problem is that fuel produced for general aircraft makes up less than one percent of the fuel sold for all of aviation,” said Renno. “So there really is no economic incentive for companies to develop such a fuel, unless they get help from the government.”

The quest for an unleaded avgas that will deliver high, safe performance has been an arduous undertaking. Under the Clean Air Act (CAA), the Environmental Protection Agency (EPA) has the authority (in consultation with the FAA) to regulate emissions from aircraft. There have been talks in the works since 2010 to rid avgas of lead. In 2013, the FAA announced the formation of the Piston Aviation Fuel Initiative, a joint effort between the FAA and industry partners with the goal of formulating an unleaded replacement fuel that could be used by the entire general aviation fleet by 2018. This has yet to happen and now the deadline has been pushed back to 2030 for a complete ban on leaded avgas.

In 2012, this committee released a report that included five key recommendations to facilitate the development and deployment of a replacement unleaded aviation gasoline. The plan called for bolstered research and development funding across government and private industry sectors to formulate unleaded avgas by 2018.

To meet this goal, the FAA in June of 2014 petitioned the world’s fuel producers to submit proposals to help the general aviation industry make a transition to an unleaded fuel and received 17 submissions from six manufacturers. After an initial review from a technical evaluation committee, four were selected into a testing phase one, which began in 2015. After another review from the technical evaluation committee, two fuels were selected from two companies – Swift and Shell – to move onto phase two, which revealed issues during engine and aircraft testing, and testing was halted in 2018.

Swift announced that it was suspending its work for this sector as Shell continues its research on this type of fuel formulation.

At this time, the FAA stated that it was seeking new authorization to use unleaded fuel in engine and aircraft, which was granted in October 2018.

Unfortunately, the FAA stated that differences in the Piston Aviation Fuels Initiative fuels as compared to 100LL had issues and were evaluated for impacts and mitigations and testing completions again were projected for the end of 2021.

A third initiative as part of the 2012 FAA Modernization and Reform Act established an unleaded aviation gasoline research and development program with deliverable requirements. The FAA has issued the Unleaded Avgas Transition (UAT) Action Plan that will integrate these three activities.

The fourth initiative involves private-sector companies that have applied for supplemental type certificates for specific piston engine and aircraft models to operate with new, unleaded aviation gasoline formulations. The FAA stated it is actively working to support all of these initiatives. Now, the FAA, along with the EPA, stated that benchmark can be met by 2030 or sooner.

In tandem with the quest for an alternative fuel has been the push on the EPA to strengthen restrictions on using leaded avgas from environmental and grassroots activists, from local government officials who cannot make changes to federal law, to academic researchers whose work provides the evidence as why ending leaded avgas is vital to the overall health and wellbeing of the general population.

Much of the information on avgas, the number of general aviation aircraft and airports, the history of attempts to regulate avgas and health implications of lead exposure for this report were sourced from research studies mentioned below.

Lead contamination occurs through inhalation or ingestion of lead in food, water, soil, or dust particles. The heavy metal primarily accumulates in the body’s blood, bones and soft tissues and damages the nervous system as well as the cardiovascular system, reproductive system, blood, kidneys and other organs. Excessive lead exposure during early childhood is associated with lower IQ scores and neurological impairment such as seizures, mental development and behavioral disorders. Even at low doses, lead exposure may be a factor in high blood pressure and subsequent heart disease.

In 2006, the environmental group Friends of the Earth petitioned the EPA to officially designate the danger coming from lead emissions from PEAs and better regulate the general aircraft industry. While both the EPA and the Centers for Disease Control have historically concluded there is no known safe level of lead exposure, the EPA ruled against the petition, calling for more studies to substantiate the risks.

In late 2008, the EPA established more stringent National Ambient Air Quality Standards (NAAQS) for lead concentrations, changing the standard from 1.5 micrograms per cubic meter that can be measured in the span of four months to 0.15 micrograms per cubic meter measured over a three-month rolling average.

In conjunction with lowering the lead NAAQS, the EPA required monitors to be placed in areas near industrial facilities with estimated lead emissions of 0.50 tons or more per year, at airports with estimated emissions of one ton or more per year, and on a case-by-case basis in locations where information indicates a significant likelihood of exceeding the standard.

This lead monitoring is conducted by state and local air quality agencies such as the Michigan Department of Environment, Great Lakes and Energy (EGLE).

In 2010, the EPA released a monitoring study from data collected in 2008 on 17 airports that had estimated lead emissions greater than or equal to 0.50 tons per year and less than one ton per year, airports that had greater frequency of operations from one or two runways and ambient air within 150 meters of the locations of maximum emissions. In this study, Oakland County International Airport had a reading of .59 tons of annual lead emissions. The airport with the most lead emissions, at 1.32 tons, was Phoenix Deer Valley in Maricopa County, Arizona.

According to the latest data from 2020 in the EPA’s National Emissions Inventory, OCIA released .262 tons of lead; Oakland/Troy Airport released .069 tons of lead; and Oakland/Southwest Airport in New Hudson released .030 tons of lead.

The EPA in 2020 released a study titled “Model-extrapolated Estimates of Airborne Lead Concentrations at U.S. Airports.” It was developed to provide estimated ranges of lead concentrations that may occur at and near airports where leaded avgas is used. The study estimated air lead concentrations at the “maximum impact area” around over 13,000 U.S. airports and took into account airport-specific information such as the kinds of aircraft the airport hosted and the amount of takeoffs and landings that take place annually. The study concluded that the crucial area studied lies just at the end of the runway where pilots are required to conduct safety checks with engines running just prior to takeoff.

“This area is expected to have the highest concentration of lead in air, and in fact air monitoring has reported concentrations of lead above the lead NAAQS near some airports,” explained the EPA’s Brann. “The model-extrapolated lead estimates in this study indicate that some additional U.S. airports may have air lead concentrations above the NAAQS at this area of maximum impact. The airports in Oakland County were not among them. The report also shows that estimated lead concentrations at airports that may have concentrations above the NAAQS decrease to below the standard within 50 meters from the area of highest concentration.”

The EPA in 2020 also released a report titled, “National Analysis of the Populations Residing Near or Attending School Near U.S. Airports.” The report was written with the intent to show the contrast of the larger footprints of the nation’s 500 larger, commercial airports, whose landing strips are located at large distances from residential areas, and the nation’s some 20,000 smaller general aviation airports, which may have setbacks of less than 50 meters from residential and recreational areas.

The EPA and local air quality management district studies indicate that over a three-month averaging time (the averaging time for the EPA National Ambient Air Quality Standard for Lead), the impact of aircraft lead emissions at highly active airports extends to approximately 500 m downwind from the runway. These same studies suggest that on individual days, the impact of aircraft lead emissions can extend to almost/ 1,000m downwind from the runway of a highly active airport.

This study indicated that 5,179,000 people live in census blocks within 500 meters of these runways, and 363,000 ofthem are children aged five and under.

On October 17, 2022, the EPA issued a proposed determination that lead emissions from certain aircraft cause or contribute to lead air pollution which may reasonably be anticipated to endanger public health and welfare under section 231(a) of the Clean Air Act.

Late in 2022, the agency began collecting comments from the public on the proposed determination. Included in these submissions was a January 17, 2023 letter signed by public officials from California to Texas to Massachusetts. In the letter, officials expressed both their concern of the use of leaded gas from a public health and a child development standpoint and their frustration in the slow progress to find alternative, unleaded fuels, lax regulations at the federal level in not being able to do anything about, such as passing regulations, from a local level.

“A rapid phaseout of lead from avgas is technologically feasible and can be done safely, without undue cost,” the letter stated. “The FAA has already certified a fully unleaded fuel that is safe for use by the entire piston-engine fleet (which at the time was only being used in Santa Clara County, California). Urgent action is further compelled by the Biden-Harris Administration’s and the EPA’s own commitments to advancing environmental justice, including the EPA’s recent strategy to reduce lead exposures in communities overburdened by pollution. Moreover, rapidly banning leaded avgas is ethically necessary. In the decades that this endangerment finding has been pending, millions of children nationwide have suffered irreversible harm from unregulated leaded avgas. We ask that the EPA finalize its proposed findings and fulfill its mandate by quickly eliminating this pollutant.”

It continued: “Though the EPA presents leaded avgas primarily as a danger to public health, the societal costs of this lead exposure also do profound harm to the public welfare. The Clean Air Act section 302(h) defines ‘welfare’ to include ‘effects on economic values and on personal comfort and well-being, whether caused by transformation, conversion, or combination with other air pollutants.’”

The signatories of the letter contended that as local government officials, they have little power to control, limit or restrict how many general aircraft take off and land in their localities, nor do they have the authority to ban aircraft using leaded avgas.

One of the local signatories of the letter to the EPA was Washtenaw Prosecuting Attorney Eli Shavit. His county is home to five general aviation airports including Ann Arbor Municipal Airport, which hosts more than 180 aircraft and handles approximately 75,000 annual operations. “There is significant scientific evidence that leaded aircraft gas can harm children,” said Shavit. “We have seen this through a number of other contexts, including use of leaded gas in the past, lead paint, and of course, we are all too familiar with the danger of lead service lines in Michigan. For that reason, we need the EPA to appropriately regulate avgas and take necessary steps to protect our children.”

Shavit said that no lawsuits or cases have been brought to his office against smaller airports that host single piston engine aircraft, and he is unsure that if any case arose, it could even be tried at a local level.

“I’m not entirely sure that we would have the legal authority to do something like that (on a county level). Air regulation is done primarily at the federal level by the FAA and it’s up to the EPA to regulate substances such as fuel. The only thing we can do for public health, especially the health of young children with developing brains is advocacy, and that is what we are doing.”

According to EPA spokesperson Khanya Brann, the agency has been spending 2023 reviewing and considering all the comments that were provided to the EPA regarding its proposed finding.

“In the fall of this year, we plan to issue the EPA’s final determination on this matter,” Brann stated. “If EPA makes a final determination that aircraft engine lead emissions cause or contribute to lead air pollution that may reasonably be anticipated to endanger public health or welfare, the EPA would have a duty to propose and promulgate regulatory standards for lead emissions from aircraft engines. Should EPA make this final determination, the FAA would also become subject to a duty under their authority to prescribe standards for the composition or chemical or physical properties of aircraft fuel to control or eliminate aircraft lead emissions. It is premature to speculate on the timing and content of any possible follow-on regulatory actions at this stage in the process.”

At the state level, in 2017, the Michigan Department of Environment, Great Lakes and Energy (EGLE) reported that the largest emitter of airborne lead by sector were mobile vehicles, meaning single-engine piston aircraft, at 10 short tons per year. However, this measurement was at a cumulative, state-wide amount, and most smaller airports servicing general aircraft only have to report if their emissions exceed one metric ton per year. According to EGLE Spokesperson Jeff Johnston, Michigan’s airports do not exceed this level.

According to EGLE’s 2022 Air Quality Division Monitoring Report, some of the counties with the highest emissions of lead – between .0002 - .0016 metric tons per square mile – are in southeast Michigan. Still, they fall below the latest EPA NAAQS levels for lead.

“EGLE conducts ambient air pollution monitoring through a network of 40 monitoring sites statewide for six air contaminants including lead,” said Johnston. “As of 2022, the entire state of Michigan is in attainment for lead, carbon dioxide, nitrous oxide and particulate matter. Lead levels are well within NAAQS standards at all locations. One of the 40 monitoring sites is in Oak Park, about five miles from OCIA.”

Johnston maintained that EGLE’s regulatory role is over stationary sources of air pollution – such as industrial sites like lead smelters, and not vehicles such as aircraft.

Though Cheryl Bush, the OCIA’s regulatory manager, could not be reached for comment, Oakland County spokesperson Bill Mullan maintained that airports which service general aviation aircraft have few regulations when it comes to lead testing and monitoring.

“Airports who host these aircraft are not required to test for lead emissions in the air, or in the blood of children who live and/or go to school around these airports,” said Mullan. “Sustainability and healthy residents are two of Oakland County’s strategic goals. Eliminating the use of lead in aviation fuel is a necessity to ensure a healthier future for our residents and we support the FAA’s goal to eliminate lead in aviation gas by 2030. We hope they can reach that goal even sooner. Oakland County International Airport is proud it will be participating in EGLE’s PurpleAir monitoring program, which will be installed at the airport.”

The most recent study to offer laser focus on the threat faced by children exposed to avgas emissions was “Leaded Aviation Gasoline Exposure Risk and Child Blood Lead Levels,” published in the January 2023 issue of Proceedings of the National Academy of Sciences (PNAS). Researchers included Sammy Zahran, affiliated with the Department of

Economics and Department of Epidemiology at Colorado State University, Christopher Keyes, affiliated with the Department of Economics at Colorado State University and the Mountain Data Group of Fort Collins, Colorado.

This study analyzed over 14,000 blood lead samples of children aged five years and younger residing near the Reid-Hillview Airport in Santa Clara County, California between January 2011 to December 2020. Researchers discovered that the closer the children lived to the airport, the higher their blood lead levels, especially those who live east and downwind from the airport. Blood lead levels also increased depending on the amount of airport activity and the amount of avgas sold at the airport.

Subsequently, after these samples were taken, Santa Clara County became the first and only place in the country which banned the sale of 100LL at Reid-Hillview and San Martin Airports in January 2022, according to General Aviation News. Now, these airports only sell 94-octane unleaded avgas and jet fuel and expect to be among the first in the nation to sell 100-octane unleaded avgas.

The study published in PNAS referenced an earlier study, “The Effect of Leaded Aviation Gasoline on Blood Lead in Children,” published in July 2017 in the Journal of Environmental Economics (Sammy Zahran, Colorado State University; Terrence William Iverson, Colorado State University; Shawn P. McElmurray, Wayne State University; Stephan Weiler, Colorado State University).

In this study, researchers poured through data from 400 census tracts in proximity to 448 airports and airstrips in Michigan. Of the 400 census tracts within two kilometers of an airport in Michigan, 41 percent also live within two kilometers of a lead-emitting industrial facility.

The study collected data of the blood lead levels in children in the months prior and immediately following the September 11, 2001, terrorist attacks through December 2009 in a confidentiality agreement with the Michigan Department of Community Health, now known as the Michigan Department of Health and Human Services. The data contains blood samples from 1,043,391 children under the Healthy Homes and Lead Poisoning Prevention program. At the time, that number was representational of one-sixteenth of all children under 72 months in Michigan.

Upon their findings, researchers issued the following: “Children exposed to lead have diminished life chances. Studies link lead exposure to adverse mental and behavioral outcomes, such as IQ loss, poor academic achievement, attention-deficit disorders, delinquency, and violence and to irreversible physical health problems such as hypertensive disorders, damage to renal and cardiovascular systems, and tooth decay.”

Blood lead level data are reported in units of micrograms per deciliter of blood (mg/dL).

Previously, Zahran, Keyes, and other researchers in a 2011 study analyzed blood lead levels as a variable of less than five micrograms per deciliter of blood and (greater than or equal to 5mg/dL 5.1, less than 5mg/dL 5.0, and greater than or equal to 10mg/dL 5.1, and less than 10mg/dL 5.0). They used these thresholds of greater than or equal to 5 and greater than or equal to10 mg/dL because they corresponded to the CDC’s present and past reference levels of elevated blood lead. Children with blood lead levels exceeding these “levels of concern” required case management. Secondly, they reported that 40.2 percent of children sampled have blood lead levels that are at or below test detection limits.

Some of these children could have been living in older homes where lead paint is more present, which could have inflated estimated health risks from avgas exposure. This coincidental problem was addressed by including neighborhood factors of housing age and location of industrial points within each census tract.

In addition to factoring in possible additional lead exposure points, researchers also took into account other variables, such as volatility of wind patterns and fluctuations in general aviation traffic that can also impact the blood test results, so much so that two children living the same distance from the same airport may have different blood lead levels depending on the angle of the child’s home and school.

In Michigan, populations of lower socioeconomic and educational status are more likely to reside within two kilometers of an airport compared to those who may live in neighborhoods at least 10 kilometers away.

The researchers also accounted for concentrations of legacy lead in soils, left behind from decades of leaded automotive gasoline, which they said is an underappreciated source of lead exposure.

Across all their testing and datasets, one thing remained consistent: the use of avgas was significantly linked to elevated blood lead levels in children living near airports.

The researchers recommended a reduction of flights in the summer months, when children are outside and may already be playing in fields already polluted with legacy lead dust. Can there be a price tag put on the harm caused to children living, playing and learning within a flight path of aircraft fueled by leaded avgas? Researchers think so.

The 2017 study stated: “We find that reducing PEA traffic in Michigan from the

50th national percentile (407 monthly operations) to the 10th percentile (133 operations) would generate a social benefit, measured in terms of the net present value of future earnings, of about $120 million. This translates to a bit over $10 in external social cost per gallon of avgas sold, which can be compared to a pump price of about $6 per gallon. This estimate may be regarded as conservative because we consider only deposition near airports on a subset of the population (children under five), and we only account for the impact of IQ loss on earnings, one of several known damage channels.”

Zahran, Keyes and other researchers noted that a hypothetical reduction in PEA traffic from the 50th to the 10th percentile would generate a five-year cohort benefit of $126 million for Michigan and $4.9 billion nationwide.

Accompanying such a reduction, the number of children falling below the CDC current reference threshold of 5 mg/dL would also increase by about 1,600 children in Michigan and 64,000 children nationwide. To put this in perspective, the recent catastrophic failure of the water treatment system in Flint, Michigan, increased the number of children with elevated BLLs by approximately 200. Researchers contend that this comparison is imperfect since the Flint water crisis occurred at a different time period, with a lower baseline fraction of children with BLLs ≥5 mg/dL, and because the Flint case involved explicit acts of commission.

In an email exchange with Downtown Newsmagazine, Keyes emphasized the importance of studying the adverse health impacts lead can have through this lens in order to affect changes in policy and regulation.

“Before we can do anything from a policy perspective, we need some sense of the benefits of minimizing the risk against the cost of doing so,” Keyes wrote. “Environmental regulations are required by the federal government to pass a benefit cost analysis before being enacted. Our research on lead exposure aims to provide evidence which can aid policy makers in their decision making, as well as inform the general public in their understanding of this particular risk factor.”

Keyes added that other health economists in earlier studies from 1994, 2002 and 2009, have linked lead exposure and childhood blood lead levels to lost IQ points and how this will impact a child’s

future income earnings. For example, a one-IQ-point gain results in an estimated gain in the present discounted value of lifetime earnings of roughly $22,000.

Keyes explained: “Starting with childhood lead exposure as measured by blood lead levels, we can estimate the expected gain in IQ points attributable to a reduction in lead exposure from avgas emissions. Multiplying the expected gain in IQ points times earnings per IQ point provides a rough estimate of the social benefits from the reduction of source lead exposure.”

Keyes reiterated that lead exposure comes from a multitude of sources: paint chips in aging homes, older toys, soldering that comes off in older copper piping. Exposure to lead from avgas is also determined by numerous factors: proximity to living, playing or attending school near a general aviation runway, prevailing wind direction, and the volume of piston engine aircraft traffic.

But Keyes fears that unlike the Flint Water Crisis, which was a well-defined one-time episode that is now finally being addressed, exposure to lead from avgas continues from thousands of airports all across the nation.

“From a public health risk perspective, the Flint Water Crisis was a one-time episode, while piston engine aircraft emissions are an unabated source of lead exposure occurring seven days a week, 365 days a year.”

Keyes said it is the job of researchers to stay out of politics and provide the evidence and the data to then be reviewed by agencies such as the FAA and the EPA. It is then up to policy makers to make changes.

“Ultimately it is up to policy makers, we just supply information,” said Keyes. “Authorities must work through the on-balance implications of making the transition to unleaded fuels. From an economic standpoint, the benefits are sizable and lasting. To the extent that the alternatives are made widely available to the aviation community, it is my understanding that they want to transition to unleaded avgas as much as anyone else.”

Even so, health experts have long known that the only acceptable level of lead spewed into the environment, whether in our water infrastructure or in the air, is zero.

At the grassroots level there are a few local residents who have made it their mission to make sure this issue stays front and center to local government officials and make other residents aware of the dangers of living downwind from runways that host PEAs. They wish Michigan’s county governments would go the route of Santa Clara County and swap in unleaded high-octane avgas.

Matthew Grisius of Canton, retired from working as a consultant in defense, aviation and aeronautics, describes himself as an angry and concerned taxpaying father and grandfather. He has spoken out on the issue for 25 years to limit and even completely restrict the flight of aircraft which use avgas.

The population density of Canton is 2,700 people per square mile, and all are in the flight path of the 1D2 Canton-Plymouth Mettetal Airport. The airport also lies two miles south of Plymouth.

Operational since the 1930’s, it is a small airstrip operated by the Michigan Department of Transportation. The facility runs about 38 flights per day and hosts 78 aircraft, most of them PEAs, plus three multi-engine planes and three helicopters.

The airport’s manager, Jim Morency, said the airport has not received many complaints or concerns about lead air emissions from school officials or neighboring residents. According to his records, the airport is busiest in the warmer months, as general aircraft are unheated. He said on average, there are about 20 flights per week between April and November, and traffic is light as the airport does not offer flight instruction.

But Grisius argues otherwise. His grown children attended schools just across the street from the airstrip and have suffered from chronic learning and emotional disabilities. He has friends whose children went to Plymouth Christian Academy who also told him they also had behavioral problems. Grisius said there was never a notification to have their children’s blood tested for lead. But in his opinion, what is known about lead contamination should be enough evidence to limit – and even ban – what he describes as unnecessary flight activities that are enjoyed by those wealthy enough to fly their own aircraft.

“There is nothing like rules or regulations or advisories from government that warns people living next to an airport of their risks,” Grisius said. “There are no regulations and no warnings. And airports don’t have to say anything about it. That’s why I call the use of this leaded gas a well-kept secret.”

For decades, Grisius has tried to bring this up in public comment sections at local meetings and is frustrated with decades of inaction to even reduce the number of flights at the airstrip. He keeps up a blog, Close 1D2 – Canton-Plymouth Mettetal Airport, that documents activities, has articles on avgas and lead poisoning, research papers, contact information for local, state and federal government representatives, and documented reports that back up his opinion that it is now safe for all PEAs to switch to unleaded avgas. He believes that flight hobbyists and lobbyists are responsible for holding back progress in removing lead from avgas because smaller planes are for the rich and there is much profit to gain.

“For the most part, those who are using these planes are rich hobbyists,” Grisius said. “There is no vital reason these planes need to be flying and it does nothing to progress anything.”

His blog includes links to a 2019 report which showed that autism rates in schoolchildren in the Plymouth-Canton school district had increased by 47 percent since 2010.

Grisius pointed to the fact that the school district cannot keep up, pay for, or find the kinds of specialized teachers, therapists, and paraprofessionals it needs to address the burgeoning number of children with learning or behavioral difficulties. And though there is a direct link between lead exposure and these neurological disorders, there has been little to no testing of blood lead levels in the school district.

“Plymouth-Canton Schools need to employ a great amount of special education teachers, but nobody wants to conduct (blood lead level) testing,” asserted Grisius. “They know that lead is a problem; they know about the connection between lead exposure and neurological and epidemiological development in children. If you bring this up (at a board of education or township meeting), pilots for a little while will shift their activity. They might fly less for a little while. But at one time, there was about 200 general aircraft hosted (at Mettettal). And there were about 30,000 monthly operations, so I don’t believe any of the official statistics.”

Jim Coon is senior vice president of government affairs and advocacy of the Aircraft Owners and Pilots Association, an organization formed in the 1930’s to promote enthusiasm for 300,000 flying hobbyists. He maintains that his organization wants to find an end to the use of leaded avgas.

Coon said that the entire fleet of aviation aircraft uses 180 million gallons of avgas per year. That’s the same amount that all the automobiles in the United States use in four hours.

“All those automobiles at one point used leaded fuel, so you can see why it was important to first tackle the leaded gasoline challenge used by cars first,” justified Coon. He said his organization, along with hundreds of other representatives in the private and public sector, are working with the FAA to eradicate the use of lead in avgas by 2030, just as the FAA is striving for a goal of 2050 to be carbon emission neutral.

“There is no fight or opposition here, we as general aviation flying enthusiasts want to remove lead from our fuel as soon as possible,” he said. “The brightest chemists and engineers have been working on this and if it were easy to formulate a lead-free fuel that would be safe to use across the wide range and types of aircraft and engines that are out there, we’d be using it by now.” ­


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