However, I don't think anyone can argue that the effects of a 'local', limited, nuclear exchange are not local. The +49 day map of smoke particles, if not exact, isn't likely to be too far wrong. What it doesn't cover, for some reason, is the spread of nuclear contamination. That number of small yield weapons would put a lot (I'm not even going to start working it out) of radionucleides into the atmosphere. Some of those have short half lives, but create a severe and (near) immediate hazard to life. Some have very long half lives and could present a long-lasting and global threat to life.
Okay, possibly, but I ask you this, where are all these threats to life you speak of when one considers all of the above ground nuclear bomb testing and the US, USSR, China and France did in the 50s-70s?
I am not inferring nor suggesting in any form or fashion that having a nuclear exchange, even as limited as this would be, should the unthinkable happen, not be dangerous and do harm, but we cannot lose sight of historical facts.