All virii can live in droplets suspended in the air and carried by air currents.
They differ VERY widely in how long they can survive in droplets in the air.
They also differ in how easily they can infect another person when they are breathed into the lungs or deposited on the eyes or other mucus membranes.
The common cold is extremely hardy in these respects and just a few particles breathed in will give you a cold.
Ebola is FAR less hardy in the air than the cold virus. It is possible that Ebola could someday mutate into a form more easily transmitted by airborne droplets.... perhaps a change in the protein coat could do it... make it hardier and more sticky. As it is right now Ebola is able to transfer to a new host by droplets coughed directly into ones face from less than three feet.... picture a wet cough of such magnitude that you need to wipe your face off or rub the droplets from your eyes.
And yet it spreads....