Aerosol pollution indeed cools the Earth:

https://climate.nasa.gov/explore/ask-nasa-climate/3271/aerosols-small-particles-with-big-climate-effects/

I might add that given that Asimov's article was written in 1974, you'd be a bad scientist if you didn't expect that some parts of the picture would have changed in the last fifty years. But then we have already established that fact, haven't we?