• Breakdown and Removal Efficiency (DRE) is a percentage that is the number of compound molecules removed or destroyed in the incinerator relative to the number of molecules entering the system. (For example, a DRE of 99.99 percent means that 9,999 molecules are destroyed for every 10,000 molecules that pass through. A percentage of 99.99 is known as “four nines”. The strict as “six nines”.)