Pentane is the most common expansion agent in EPS production. Low concentration of pentane can be trapped during production, inside the closed cells of EPS. By the end of the production cycle, EPS products may still contain 1-2% of Pentane by weight (Dongying Liangxin Petrochemical Technology Development Limited Company, a subsidiary of Junyuan Petroleum Group) . At this concentration, pentane can build up in the air around EPS at concentrations way above the flammability point or exceed the occupational exposure limit for pentane.