It was a pretty good article for the 60's. It mentioned carbon dioxide as a warming influence and particulate matter as a cooling influence. That hasn't changed. What has changed is that we now have a better understanding of the quantitative impact of each. I don't have the link at my fingertips, but there was a literature search of actual scientific climate papers in that time period, and a majority favored the warming hypothesis, but a significant minority favored the cooling hypothesis. You can probably find it in skeptical science or Coby Beck's blog.
I was arguing about that with a chemtrailer last night. I said the Clinton administration wouldn't have done it because the scientific consensus on global warming was not rock solid until the 2001 IPCC report, and the next commander in chief, along with most of his party, thought global warming was nonsense. He mentioned a '60s paper by Carl Sagan as evidence everybody knew about global warming back then.