Biological warfare encompasses a mixed bag of bacterial agents, viruses and toxins, Wade explained. Lumping all biological warfare agents together as a class is almost as dangerous as comparing biological and chemical agents directly, because they can be very different, he said. Depending on the situation, some are contagious, others are not. But when we leave the room, we may not necessarily 'spread it' in a contagious sense, unless some of the agent remains on our clothing and is physically transferred to someone else. Usually, people think of biological agents as an aerosol threat, according to the Pentagon expert.
Aerosols behave a lot like chemical vapors.
There's a lot of water vapor in a room, but we can't see it, or feel it, or taste it, or touch it. That's really what we'd have in a biological event. Most biological agents don't weather well. You put them out in ultraviolet light and they die. They don't like drying out.