VX is more of a skin hazard than inhalation hazard, but it can be an inhalation hazard if aerosolized. They inhibit the build up of acetylcholine in the body. This stimulates every organ in your body and does not stop. In the pure state, Tabun, Sarin and Soman are colorless and only have a mild odor. VX may have a slight yellow color.
All nerve agents are heavier than air.
First responders will determine that a nerve agent has been utilized in an attack by observing the signs and symptoms of the victims. Symptoms include but are not limited to, pinpointing of the pupils, diminishing vision, runny nose, difficulty in breathing, chest pain and seizures. Remember the patient's clothing and all personal articles are considered potentially contaminated evidence. Any explosion with minor damage, should be a clue that the device may have delivered some type of Chemical, Biological or Radiological Agent.