Pollution emitted by aircrafts will kill at least 8000 people this year alone, a recent study has estimated.
Researchers from MIT say that nitrogen oxides and sulphur oxides emitted by aircraft at approximately 35,000 feat combine with other gases in the atmosphere to create noxious particulate matter.
Earlier studies of the effects of aircraft pollution on air quality have focused on landing and takeoff emissions as most airline fuel gets burned at high altitudes.
"Anything above that [altitude] really hasn't been regulated, and the goal of this research was to determine whether that was really justified," CBS News quoted lead author Steven Barrett.
But the risk isn't necessarily greatest over the northern hemisphere, where the heaviest concentration of commercial aviation flights take place. Taken eastward by high-speed winds, the emissions spread to other continents where they extract a proportionately heavier toll in China and India, according to the study.
"Even though the amount of fuel burned by aircraft over India and China accounts for only 10 percent of the estimated total amount of fuel burned by aircraft across the globe, the two countries incur nearly half - about 3,500 - of the annual deaths related to aircraft cruise emissions," he added.
The report is published in the journal Environmental Science and Technology.