Aerosolized is not the same as "airborne" in the classic understanding of the term. But, it's a virus in its like, what? 25th generation in this outbreak. It's already weakened itself in order for its host to live longer and pass the infection along with a greater chance to find a new host. It people are picking it up from either surfaces or inhaled particles, it's really hard to tell. Best options are to expect that it will kill the over-confident, inattentive, or arrogant. Plenty of targets for that here in the U.S.
He`s saying that the present studies show that the tiniest droplets of, lets say a sneeze of cough, do not pose as great a danger in the hot and humid environment of Equatorial Africa as the virus will quickly go inactive due to environmental stresses, but, as the USAMRIID study showed, lower the temps and relative humidity and the virus has a much longer survivability outside the body.
Now for the virus embedded in it`s droplet which is floating thru the air, this opens the window of infectious opportunity. Someone sneezes in a cold and dry space, like a subway, and that droplet, with it`s cold preserved Ebola virus, floats around for extended periods of time and should be capable of causing infection.
The virus doesn’t change itself. The strains that are better able to incubate longer and spread easier, and result in a lower fatality rate fare better, having a non-human reservoir helps as well, so that even when the germ appears gone, it can re-emerge much later and cause another outbreak. Given that we also have pigs and bats in America, we should be extra sure that potential infectees do not have contact with possible non-human reservoirs .