Experts have shed light onto how sunlight transforms jet engine exhaust to potentially toxic particles.
In the groundbreaking study, researchers from the Carnegie Mellon University in Pittsburgh, US, have discovered that drops of oil created by idling aircraft engines can over time turn into tiny particles that can easily penetrate the lungs and brain.
In the first study of its kind, the researchers collected pollution from an idling commercial plane as it operated at different loads.
When the jet operated at full power the emissions were composed of mainly solid particles, however when it idled on the runway they took on a different form - microscopic droplets.
"The magnitude and composition of these emissions strongly depend on engine load, with much higher emissions at low engine loads," the study said.
However when the exhaust was exposed to sunlight in a "smog chamber" a chemical reaction took place that saw the formation of toxic particles from the interaction between the oil and gases.
It was found that sunlight could generate 35 times more particles than were originally emitted from the jet's engine and 10 times what had typically been predicted.
These particles can include compounds such as benzene and toluene, which are known to impact health.
"Smog chamber experiments indicate that photo-oxidation of aircraft emissions produces significant amounts of secondary PM (particulate matter), which, under typical summertime conditions, exceed the primary emissions within minutes of the exhaust leaving the engine."
Allen Robinson of Carnegie Mellon University said the results were "unbelievable".
"It sort of blew our minds," the Courier Mail quoted Robinson as saying.
The study has been detailed in the Atmospheric Chemistry and Physics Journal.