Cant it become airborn?
Are You a Terrorist?
If someone started engineering the actual virus: YES; otherwise, it required a numbers of mutations to become airborn-transmissible.
I can only imagine what kind of fun airborn stuff area 51 has after half a century of research in complete secret from the public. Also how did the CI..... HIV virus start? Airborn is definetly possible considering what kind of stuff the USA has done in the past.
EDIT: China propably have a lot of fun stuff too as well as Russia, but I dont think US, RU or CH are going to release an airborne version of the virus... Once you know biology and chemistry it's not that hard (I don't know either of those very well), evil people run this world and they will be up to shady stuff, but killing us off wont happen anytime soon. Also are you one of the people who thinks that the terrorists are muslims in 95%+ of the cases?
I read once the most dangeuros and common hazard there was the dumping of exotic materials & other byproducts in open pits to burn. I don't know if it's an enduring practice. However if they do BW research or manufacturing they'll use (i doubt, but i can disprove it with Open-Source docs) they will surely protects their workforce since people with PhDs cost a lot more to replace than Lumberjacks.
Industrial accidents in the BW plants already occurred and get known.
Accidents in Soviets'programs, .
Most dangerous for the workers maybe, and that is true they all end up with radiation poisoning or cancer from the stuff they burn. Wikipedia source? Doesn't say much, we all know that chem warfare has existed since WW I and they have had a few decades to improve it since then, you know they don't show us everything right?
The US Goverment denied the very existence of Area 51 untill mid 2013, do you know any more information about whats going on in there since then? Still hush hush secret secret and you get killed on sight if you come to close no questions asked why, what reason? Only one I can come up with is secret research, and seeing how US is a big war machine they propably do researchs in all and are way further ahead then they want to share with avarage Joe (and why would they, good to have aces in your sleeve), same goes for the other 2 biggies. China has been spotted on google maps driving trucks (and not one truck) into mountain made tunnels/facilities, who knows what's going on there?
Take for instance how they changed their warfare in Afghanistan; from slow loud fuel burning helis to scilent fast (way deadlier) remote controlled drones. No men are put in harms way (except enemy ofc), which is a big step, or huge leap in modern warfare, now enemy has no chance to fight with their rpg and their AK47's - I've seen vids where Afghani people just lie down on the ground waiting to die when they notice a drone is near.
Where to make those machines as effective as possible without anyone knowing about the research and what to come? In a facility where avarage Joe gets killed on sight if he is to near it would be my guess.