Leaded gasoline had a big impact https://today.duke.edu/2022/03/lead-exposure-last-century-shrunk-iq-scores-half-americans
CO2 I imagine very similar lower individual impact but way more widespread.
Leaded gasoline had a big impact https://today.duke.edu/2022/03/lead-exposure-last-century-shrunk-iq-scores-half-americans
CO2 I imagine very similar lower individual impact but way more widespread.