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-m...

Volume of 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.