The Symptoms of (MIC) are "difficulty breathing, pressure on the chest while breathing, pulmonary oedema, watery eyes, burning skin sensations etc." (The World Book Encyclopedia CD-ROM.) .
There were many nerve agents that were created during the time that world war one and world war two had taken place. "Some of these nerve agents include VX gas, Nerve gas, Sarin gas, Cyanide gas, Mustard gas, and chlorine gas, finally phosgene gas."(Unknown Uky.edu~holler ) The most harmful out of all these listed here would be the VX gas. "(Unknown Grolier encyclopedia) It has the capabilities to eat the skin right off of the spot where it makes contact, when it is in its liquid form. "When it is in its gaseous form it capable of making a distance miles and still be deadly enough to kill."(Unknown chemical origins) In order to prevent being harmed by any of these things you need to get some form of protection for yourself; So that you can avoid an accidental mishap. They now have high quality protection. Things like gas masks and biochemical suits. "United States is the most high tech protection around."(Grolier Encyclopedia Unknown Author 1st edition 1994.") .
The second most deadly nerve agent would be Sarin gas. In it's liquid form it is most deadly and potent. It was used in prisons and Jewish extermination camps during world war two. They would take the prisoner, and tie him or her to a bed or a wall and insert the needle in either their leg, or a vein in their arm. Another way that they would kill them is by inserting them in to big gas chambers. Big groups of people at a time and close the doors, and release a substance called mustard gas in there. "They would suffer from symptoms of suffocation, Burning skin sensations, heart failure, and eventually death". (Unknown pg.3 opcw.org/chemhaz) They would be dead in a matter of ten to fifteen seconds of when the mustard gas was released into the room.
The police officers have there own form of gas they use on terrorist and criminals and it is called tear gas.