In which we hear about 19th-century observations on the heat-capacity of gases, starting with Eunice Foot in 1856 and John Tyndall a few years later. Then we get to the first mathematical modeling of Earth's climate and how concentration of certain gases affects the climate, as done by Svante Arrhenius in 1896. Then we change to leaded gasoline in the 1920s, as promoted by General Motors and its employee, Thomas Midgely, Jr. Finally, we hear of the first of four pollution diseases of Japan, Itai-Itai, discovered in 1912 as a result of mining for silver in Toyama Prefecture, but only recognized as such a half-century later.Support the show Support my podcast at https://www.patreon.com/thehistoryofchemistry Tell me how your life relates to chemistry! E-mail me at steve@historyofchem.com Get my book, O Mg! How Chemistry Came to Be, from World Scientific Publishing, https://www.worldscientific.com/worldscibooks/10.1142/12670#t=aboutBook