DEFINITION of 'Filthy Five'
A series of power plants located in Massachusetts. The Filthy Five are five plants that were constructed before 1977, and are therefore exempt from modern pollution laws. These plants emit several times the amount of pollution created by modern plants.
BREAKING DOWN 'Filthy Five'
The Filthy Five are exempt from modern pollution regulations because they were grandfathered in under the old laws. They produce large amounts of sulfur, carbon dioxide, nitrogen dioxide and mercury. The governor of Massachusetts came under political pressure to do something about these plants and issued an edict requiring them to adhere to modern pollution regulations.