One of the many ways the influenza virus can be spread is by inhaling airborne droplets from coughs and sneezes. A common way of preventing infection is to stay three feet or more away from an infected person.
The influenza virus is a contagious viral infection affecting the respiratory tract area of the nose, throat, bronchial tubes and the lungs. The two most common types of the influenza virus are types A and B.
The most common way of spreading the influenza virus is thought to be through droplets transmitted into the air from the nose and throat.
The major forms of influenza are carried and mutate within animals such as birds, pigs, humans and horses. Influenza is thought to be spread when animals cough and sneeze in close proximity to each other. It works the same way with humans, with the added wrinkle that humans also speak (and spit) to each other in close proximity.
A 2009 study from West Virginia University measured air particles in a hospital emergency department during the 2008 flu season. The study measured stationary and movable particles in the hospital, concluding that infectious particles small enough to invade the respiratory tract remained in the air for an extended period of time.
The best environment for the influenza virus to spread are cooler temperatures with low humidity levels which allow the virus to remain viable in the air for a longer period.