3 ms·

https://www.federalregister.gov/documents/2023/10/20/2023-23247/finding-that-lead-emissions-from-aircraft-engines-that-operate-on-leaded-fuel-cause-or-contribut

https://www.federalregister.gov/documents/2023/10/20/2023-23247/finding-that-lead-emissions-from-aircraft-engines-that-operate-on-leaded-fuel-cause-or-contribute-to https://www.federalregister.gov/documents/2023/10/20/2023-23... > We estimate that piston-engine aircraft have consumed approximately 38.6 billion gallons of leaded avgas in the U.S. since 1930, excluding military aircraft use of this fuel, emitting approximately 113,000 tons of lead to the air.

EnigmaFlare 3y ago
My rough estimate of the amount of naturally occurring lead in the air is 5 million tons. So 113 000 tons makes it 2% more than what it would have been with no human activity. Doesn't seem terribly serious, but not nothing either. Natural concentration of lead in atmosphere: https://www.dcceew.gov.au/environment/protection/chemicals-management/lead https://www.dcceew.gov.au/environment/protection/chemicals-m... Volume of atmosphere: https://www.reddit.com/r/askscience/comments/rf7tn/volume_of_earths_atmosphere/ https://www.reddit.com/r/askscience/comments/rf7tn/volume_of... I'm neglecting the variation in density with altitude and assuming that all that 100 years of aviation lead is still there, so it might be way off.
- D-Coder 3y ago
  That 2% will tend to be concentrated around human settlements. Every airplane starts and ends up at an airport, which will be in/near a population center.
- time4tea 3y ago
  The figures are for USA only, but you're counting the whole world. >>> import pint >>> r=pint.UnitRegistry() >>> usa = r.Quantity(9833517,"km*2") >>> h = r.Quantity(35000, "ft") >>> v = usa * h >>> naturally = r.Quantity(0.1, "ug") / r.Quantity(1, "m * 3") >>> natural_total = naturally * v >>> natural_total.to('ton') <Quantity(11563.6821, 'ton')> Natural total in USA, up to 35,000ft is 11,000 tons, and added is 113,000 tons. So the leaded avgas has added 10x. Assuming uniform distribution up to that height, and that it doesn't disappear. Neither of those things are true, especially as the lead is absorbed by people and animals.

EnigmaFlare 3y ago

My rough estimate of the amount of naturally occurring lead in the air is 5 million tons. So 113 000 tons makes it 2% more than what it would have been with no human activity. Doesn't seem terribly serious, but not nothing either. Natural concentration of lead in atmosphere: https://www.dcceew.gov.au/environment/protection/chemicals-management/lead https://www.dcceew.gov.au/environment/protection/chemicals-m... Volume of atmosphere: https://www.reddit.com/r/askscience/comments/rf7tn/volume_of_earths_atmosphere/ https://www.reddit.com/r/askscience/comments/rf7tn/volume_of... I'm neglecting the variation in density with altitude and assuming that all that 100 years of aviation lead is still there, so it might be way off.

D-Coder 3y ago
That 2% will tend to be concentrated around human settlements. Every airplane starts and ends up at an airport, which will be in/near a population center.
time4tea 3y ago
The figures are for USA only, but you're counting the whole world. >>> import pint >>> r=pint.UnitRegistry() >>> usa = r.Quantity(9833517,"km*2") >>> h = r.Quantity(35000, "ft") >>> v = usa * h >>> naturally = r.Quantity(0.1, "ug") / r.Quantity(1, "m * 3") >>> natural_total = naturally * v >>> natural_total.to('ton') <Quantity(11563.6821, 'ton')> Natural total in USA, up to 35,000ft is 11,000 tons, and added is 113,000 tons. So the leaded avgas has added 10x. Assuming uniform distribution up to that height, and that it doesn't disappear. Neither of those things are true, especially as the lead is absorbed by people and animals.