The Poison Gas is contained in artillery shells and when it is released it can become very dangerous when inhaled.
The first use of Poison Gas was used by the Germans in 1915 against the French. The Germans fired 150 tons of gas, which devastated the allied trench lines.
Impact of Poison Gas
The overall impact was that it made an easier way to harm an enemy from a long distance by simply using the wind to guide the gas. This would be a minor influence because the poison gas didn't end up killing a lot of people because of gas masks that soon became used widely.
The poison gas effected soldiers near the front line the most because of the wind blowing it over the trenches.
Positives
Simple
Only uses wind
Can wear a gas mask
Negatives
Depends on wind direction
Easily spotted
Connection to Today
The modern day example of poison gas is chemical weapons. Poison gas has improved a lot since World War I because now they can use it anywhere. It doesn't have to be just from artillery, they can drop it in bombs from airplanes. Chemical weapons have been used lately in Syria as an uprising on August 21st, 2013.