Operation Keymer was a crackdown on cannabis-growing factories in the United Kingdom during late 2006.
A Cambridgeshire Police report stated that between 25 September 2006 and 6 October 2006, nine raids took place netting them 12 arrests and over 4500 plants.
[1] The Guardian website reports 28,000 cannabis plants and 54 kilos worth £2.5 million over the same period.
Shortages were predicted to continue until February when the replacement stocks were ready to be harvested.
[citation needed] The operation is blamed for the spreading of sub-standard cannabis containing silica, a sand-like substance that when inhaled causes silicosis (a form of irreversible damage to the lungs).