It is BS, back then China, India, Brazil, Indonesia, etc weren't as industrialized as they are today, so there are actually more "sulphate aerosols" being released today in the world then there was back then when it was basically just us, yet the Earth isn't cooling.
THis photo was taken by NASA in 2005, of Aerosol pollution over Northern India and Bangladesh
My mistake the photo is from 2001 not 2005. But the arguement still stands. Nothing in the 1940's-1970's approched anywhere near as bad as that.