An increase in the use of so-called "laughing gas" as a recreational party drug has prompted police in Watford to initiate a zero tolerance policy in town pubs and clubs.

Nitrous oxide gas, which is legal and mostly used in medicine, has become popular because of its relaxing effects.

But new health warnings say abuse of laughing gas can have a number of dangerous consequences, including heart attacks and poisoning of the central nervous system.

The gas, which is inhaled by users in a balloon, has been linked to a number of deaths across the country.

Hertfordshire Constabulary is taking steps to deter the recreational use of laughing gas after a large haul of canisters was found in the county last week.

In Watford, officers are working with youths, pubs and nightclubs to ensure that those who have inhaled it are not allowed entrance to any bar or club in the town.

The police are working with the Local Government Association, which put out the health warning this week, in a bid to put additional preventative measures into effect.

The LGA warning said regular intake of the chemical can lead to oxygen deprivation, which can result in loss of blood pressure, fainting and even heart attacks.

It also warns that prolonged exposure can cause anaemia, bone marrow suppression and poisoning of the central nervous system.

Hannah Georgiou, spokeswoman for Hertfordshire Constabulary, said: "Nitrous oxide, a chemical gas, is being used increasingly as a cheap and recreational drug. While nitrous oxide is not a dangerous substance if used correctly, it can become addictive. 

"The gas is usually used for medical purposes and is always given with oxygen or air under supervision. In the wrong hands and taken incorrectly, the user may risk injury, or even death, from lack of oxygen.

"The gas can also affect a person’s judgement and cause dizziness so increasing the likelihood of having an accident.

"It is particularly dangerous to pregnant women and when used on a long term basis, can lead to a number of health issues, including incontinence and nerve damage through depletion of B vitamins. It is illegal to sell it to children."

Councillor Katie Hall, chairman of the LGA's Community Wellbeing Board, said: "It is deeply disturbing that this drug, which can be highly dangerous, is still widely viewed as safe.

"It is imperative that users understand just how harmful it can be. This gas can kill - and much more needs to be done to get this message across."

For more information visit the Talk to Frank website:

If people are worried about their use of Nitrous Oxide or other drugs they can also contact the Adolescent Drug & Alcohol Service for Hertfordshire (A-DASH) for advice and help. Phone 01992 531917 or text 07770 537227.