Aerosols

Aerosols are very effective at spread. Tiny droplets are sprayed out which

dry into a "nucleus" which and can float for long distances in the air and be

inhaled.

Eg measles- highly infectious most non-immune people exposed become

infected

TB - spread by inhaling aerosols, but need a higher infectious dose for

someone with a normal immune system, so not readily transmitted in

hospital, the exception being immuno-suppressed patients