The most deadly chemical substances include G-class nerve agents (such as “Soman”, “Sarin”, “Tabun”) and V-class (“VX”) nerve agents, which were developed in the 1940s and 1950s. Like the “Novichok” agents, which are currently frequently mentioned in the media and were developed some 20 years later, these are organophosphorous compounds that block acetylcholinesterase in the body.