It took >100 years for them to deal with it. It was often much worse than China now. In the UK, in the 1800's, millions moved to London, and lived in shocking

It took >100 years for them to deal with it. It was often much worse than China now. In the UK, in the 1800's, millions moved to London, and lived in shocking slum conditions. Life expectancy was ~30 years, diseases like cholera killed many, because of overcrowding and poor sanitation. Pollution was awful, As recently as 1952, 10,000 people died in four days in the great smog of London https://en.m.wikipedia.org/wiki/Great_Smog_of_London https://en.m.wikipedia.org/wiki/Great_Smog_of_London. In summary, it took a long time to address the problem.