Nearly one out of every 20 people breathalysed by Essex Police this month has been over the drink-drive limit.
The force has breathalysed 931 people during the first two weeks of its Christmas anti-drink drive campaign, 42 of which have tested positive.
Of those who were found to be over the limit, 38 drivers were men and four were women.
Eight of the drivers were aged under-25, the other 35 drivers were aged 25 or older.
Casualty reduction manager Adam Pipe said: "We are targeting town centres and areas where people are gathering for Christmas parties and we are handing out leaflets and giving advice.
"We don’t want to make any arrests but want people to act responsibly and make alternative travel plans if they know they will be drinking alcohol.
"There are some drivers who think they are obeying the law but are in fact breaking it by getting into their cars the morning after a night of drinking.
"We have made a number of arrests the morning after.
"Drivers need to be aware that regardless of the time of day they are caught, whether they are going to work or taking children to school, they will face the same penalties as someone who has chosen to drink heavily in a pub and driven at night.”