There is an area that has been classified, according to the IEC requirements, a being ‘Group IIA’. Compare this to something that has been classified, by the Americans or Canadians, as ‘Class I, Group A’. Which would be the most dangerous are of the two? Solution Among Group IIA and clasS I the GrouP IIA is dangerous. Group IIA contains flammable liquid ,combustible liquid and flammable gases. These are caused at the time of explosion which are dangerous. This produces high temperature which causes harmful to humans ,animals ,environment. It may releases some different gases in to earth which causes effect to environment and it may causes new health problems. This group IIA can mix with oxygen and pollute the air. Class I: It contains liquid ,vapour and flammable gas and acetylene. Which does not contains more pollution and effect when compared to Group II A. compare class I and Group II A Group IIA is dangerous and high tendency to mix with air..