A recent study conducted by the appellate authority of Andhra Pradesh Pollution Control Board (APPCB) was what eventually helped it nail the 12 erring pharmaceutical units that were issued closure notices on Thursday. Interestingly, the study in question had been allegedly initiated in connivance with the pharma companies themselves to prevent them getting blacklisted, said an APPCB source. However, the coming to light of several glaring discrepancies in the study have ensured that these firms got penalised.