The Home Office is launching a national campaign highlighting the risks of legal highs including laughing gas.
Scientists from the Government's Centre for Applied Science and Technology will go to V Festival in Chelmsford today and tomorrow to examine samples of new psychoactive substances.
They are aiming to learn which new substances are available in the UK.
Organisers of the V Festival have had a ban on legal highs in place for seven years. Chief Inspector Jonathan Hayter, from Essex Police, said: "We want to remind festival-goers that psychoactive substances will not be tolerate."