The Central Industrial Security Force (CISF) will use breathalysers to test commuters travelling in the Delhi Metro and trains for alcohol. THouse found with a significant blood alcohol level will not be allowed to board the trains and Metros. The aim is to prevent such passengers from disturbing other passengers in the often congested coaches getting into drunken brawls, which have increased of late in the Delhi Metro. Only commuters showing signs of being under the influence of alcohol will be subjected to the breathalyser. The hand-held breathalysers will generate slips of paper with the names of those whose alcohol levels are found to be high and this will help the CISF build a database of potential troublemakers.