Aviation emits an enormous amount of carcinogenic substances, much more than what is allowed in the industry. There are no restrictions on aircraft emissions, because they do not come from a chimney, but are spread over a larger area. Minister Harbers (infrastructure) is now brooding over measures, he writes to the House of Representatives, but more research is needed first.
These are ‘substances of very high concern’, and they are not called that for nothing. They can be carcinogenic and harmful to reproduction, they can alter human genes and accumulate in the food chain, and they are poorly broken down. That is why the industry must adhere to strict limit values when emitting such substances.
Aviation emissions far exceed those limit values, according to research by TNO commissioned by Minister Harbers. This is most conspicuous with formaldehyde, a substance that is indeed known to cause cancer. The industry may emit no more than 2.5 grams of this per hour on average. In 2019, Schiphol achieved an hourly average of no less than 5514 grams.
Emissions of six other substances of very high concern also greatly exceed industry standards. “Benzene is the most dangerous,” says emeritus professor of environmental chemistry Jacob de Boer, looking at the figures: 753 grams per hour, while the industry standard is a maximum of 2.5 grams. “Good Lord!”
A path with small chimneys
“I can imagine that people are concerned about that,” Harbers writes to the House. But he also wants to ‘put this data into perspective’. Those industry limits apply to what comes out of a chimney, and that directly affects the air quality around it. But aircraft engines are a mobile source: they create a ‘path with lots of little chimneys’, with much less direct consequences for the quality of the air.
Nevertheless, the area over which aviation spreads its substances of very high concern is not large. In any case, the emission figures from the TNO study only apply to the so-called LTO phase of the flight: landing from and taking off to approximately 900 metres. Moreover, within this limited part of aircraft traffic, 94 percent of harmful substances are emitted during taxiing, i.e. at the airport itself. So that ‘path with chimneys’ is not very extensive.
“For the people who work on the platforms at Schiphol, these are really worrying figures,” says De Boer. “For local residents, it depends on how far they live from Schiphol, how the wind blows and how quickly these substances become diluted. But let’s be clear: we have to get rid of these kinds of emissions.”
Standards must be enforceable
The emissions are mainly released when kerosene is not completely burned, and that happens most often when the aircraft engine is not running at full capacity – which is why taxiing is so polluting. When taxiing, let the aircraft run on one engine from now on, TNO therefore suggests, which must then deliver more power. Or use electric aircraft tugs, and in any case keep the taxi routes short.
Minister Harbers is also studying the introduction of limit values for aviation. However, the level of this must be ‘enforceable’. That is why he first wants to find out how emissions have developed in recent years and what can be expected from new, cleaner aircraft. He also wants to know exactly which substances cause the most pollution around airports. He hopes to be able to give a definite answer on this in the autumn.
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