Well I was talking about a fully terraformed Mars, but I did wonder about the transition. However, doesn't Mars thin atmosphere allow the dust to go far higher and therefore remain suspended longer than it would in a thicker atmosphere? Drag forces should act on the way up as well as the way down. It is my understanding that nuclear winter scenarios are based on launching dust into Earth's thin upper atmosphere where it remains suspended far longer than it would in the lower atmosphere. Not at all sure about this stuff as it is not something I've looked into and I'm basically cobbling together info from very different topics.

Regards,
Mark