The main chemical used in fire extinguisher is carbondioxide(CO2). The reason is that it doesnot support combustion.(Combustion is the reaction of any chemical with oxygen O2
Any chemical can be harmful in excessive amounts, and at the rate more fire-extinguishers dish them out, yes they will hurt you, or even kill you. See your local safety instructor for full details on...
Most often, simple fire extinguishers use sodium carbonate and dilute sulfuric acid to produce carbon dioxide, that extinguishes fire. small pouch carries the acid within a matrix of sodium...