PLASTIC carrier bag use in major stores has potentially reduced by 80 per cent since the introduction of an environmental levy, new figures indicate. Three months on since customers began to be charged 5p per bag, provisional data suggests a dramatic impact. There were an estimated 17.5 million bags used from April through to the end of June - with several major supermarket chains reporting an 80 per cent drop in bag usage. Last year around 300 million bag were used in Northern Ireland in 12 months. While seasonal variations need to be factored in, such as the pre-Christmas shopping surge, the figures for the first three months of the Stormont Executive levy indicate it has had the desired effect. The measure was introduced by then environment minister Alex Attwood. Mr Attwood's successor Mark H Durkan has welcomed the provisional findings. "This is great news for the environment," he said. "Our streets and hedgerows, our fields and parks should no longer be places strewn with discarded bags. In many ways the public are ahead of government here, showing a great appetite for this legislation to be introduced."