Westlake is the second-largest Chlor-alkali (chlorine and caustic soda) producer in the world, which capitalizes on globally low-cost natural gas for power in North America. Westlake is among the largest producers globally of caustic soda, which is a key building block for aluminum and polyurethanes. Chlorine is used in the manufacture of VCM and PVC, and is a key component used in water treatment by municipalities and in swimming pools.