To come in contact with tear gas when you are dreaming, can be interpreted as symbolism that you are showing emotion or sensitivity to particular relationship. Do you have feeling of suffocation by this relationship? Maybe you need to get rid of past pain and cleanse yourself.
Dream dictionary: tear gas dream meanings
To dream that you received the tear gas, denotes to depressed and unpleasant emotions that were caused by some relationships. Beware of such people who make you feel bad and take them out of your life as soon as it is possible.