As if airlines needed any more reason to reduce fleet emissions, MIT reports this week that pollution from airplanes flying at cruise altitude (approximately 35,000 feet) contributes to 8,000 deaths globally each year.
Current emissions regulations only target planes flying up to 3,000 feet. In the past, regulators assumed that emissions above the 3,000 foot mark would be dumped into a part of the atmosphere with smooth air that couldn't send pollutants drifting toward the ground (the air is more turbulent at lower altitudes). But MIT has found that that's not true—and unfortunately for those of us on the ground, 90% of aircraft fuel is burned at cruise altitudes.
Analysis of these data revealed that aircraft pollution above North America and Europe — where air travel is heaviest — adversely impacts air quality in India and China. That is, 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. The analysis also revealed that although every country in the Northern Hemisphere experienced some number of fatalities related to these emissions, almost none of the countries in the Southern Hemisphere had fatalities.
India and China are hit especially hard because pollutants from planes in the Northern Hemisphere flow eastward. Heavy farming in the two countries also leads to high concentrations of atmospheric ammonia, which reacts with oxidized NOx and SOx from airplanes to create particulate matter that people on the ground inhale.
Don't expect airlines to take immediate action. MIT is still conducting research on the topic, and the FAA is funding research of its own to address holes in MIT's study (i.e. how accurately the model reflects airplanes moving vertically from high to low altitudes). But instead of spending so much energy researching the safety of NOx and SOx emissions, perhaps everyone involved should spend more time researching low-emissions biofuels for future flights.