(Bloomberg) -- Over 370,000 UK homes could be “at risk” from toxic pollution near airports which the government underestimated by 14,000 times, according to a University of Kent study. 

The research suggests small piston-powered private planes which typically run on leaded fuel are one of the UK’s single largest sources of lead pollution, amounting to 11% of the total since 1998. That’s more than lead toxins emitted by all foundries, power stations, and lead dust created by car brake pads in towns and cities.

These piston-powered planes are typically used at airshows and by recreational pilots who fly them as a hobby. Lead is added to their fuel to increase engine power.

The findings contradict national statistics from the National Atmospheric Emissions Inventory (NAEI), managed by environmental consultancy Ricardo Plc, which provides data to the government on greenhouse gases and air pollutants. 

NAEI’s data says small private planes operating in the UK are responsible for just 0.0003% of lead air pollution, or 32 kilograms between 1998 and 2020. However, the Kent study found true number could be as high as 455 tonnes — about 14,219 times higher. 

Elevated levels of lead in blood, caused by pollution, have been linked to early death in adults and cognitive decline in children. Leaded fuel for petrol-powered cars was banned in January 2000 after campaigners successfully lobbied against it in the 1980s, and as a result overall lead pollution in the UK has fallen from 529 tonnes in 1999 to 90 tonnes in 2020, according to NAEI data.

However, even low levels of exposure to the heavy metal are toxic, and it is still prevalent in the UK and around the world. UNICEF estimates that over 229,000 children in the UK and a third of all children worldwide have elevated blood lead levels. 

A spokesperson for Ricardo, which compiles the data under an £8.8 million ($10.8 million) contract with the Department for Business, Energy and Industrial Strategy and for the Department for Energy, Food & Rural Affairs, acknowledged that lead air pollution data related to piston-powered aircraft on its website is wrong. They said new data will be published in February 2023 and will apply “a more appropriate emissions factor” suggested by researcher Ashley Mills, who led the Kent study, which “does increase UK values in the lead inventory for aviation.” BEIS and DEFRA declined to comment.

Elevated blood lead levels near airports

Lead is still added to the high-octane fuel that powers most piston-engine airplanes and some helicopters used by private pilots. Larger, jet-powered commercial aircraft use so-called “lead-free” fuel, although it still contains small amounts of the heavy metal. 

In the US, studies have found that children living within 4 kilometers of airports have elevated levels of the toxic metal in their blood. Some airports have stopped supplying leaded aviation gasoline as a result.

As part of his study, Mills applied the same 4 kilometer radius to airports in the UK, and identified 370,721 homes that sit within the boundary, potentially putting them at risk from the same levels of exposure. Aircraft emit more pollution during the take-off phase of flight, burning fuel at a faster rate to gain altitude, although it is typically only a short phase of the flight.

Mills identified tens of thousands of homes within four kilometers of airports including Rochester Airport in Kent, City Airport in Barton near Manchester, Solent Airport near Portsmouth, London Elstree Aerodrome and Nottingham City Airport. 

NAEI data is used to determine the location of the UK’s air pollution monitoring stations, which are located near potential sources of air pollution. There are currently no lead air pollution monitoring stations within the 4 kilometer boundaries identified by Mills.

An official at the National Physical Laboratory, which manages the UK heavy metals monitoring network on behalf of DEFRA and the Environment Agency, said it would make sense to re-run the UK’s air quality maps and models with the correct lead pollution information. If the altered air quality models predicted higher concentrations of lead air pollution near airports, it would trigger new requirements to place air pollution monitoring stations on site. 

Mills said the government should introduce legislation to encourage the adoption of unleaded high-octane fuel, and start actively monitoring blood lead levels in children near lead pollution sources in the UK, including airports.

Unleaded alternative

Leaded fuel used by most piston-powered planes is AVGAS100LL which has 0.56 grams of lead in each liter. Unleaded alternatives are available. UL91 is a lower-octane unleaded fuel that works in about half of small planes, but relatively few airports sell it.

A “universal” unleaded high-octane fuel called G100UL has been developed that works in all small planes, and it was approved by the US Federal Aviation Authority this year, although it is also not widely available. 

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