the NMW, the numbers of visitors has increased significantly, with more than 140,000 visiting in 2014/15, and 150,176 visitors in 2017. Intentionally preserved as an operational attraction, the site was redeveloped in 2003, with design work from TACP/Brooke Millar Partnership. The pit props and steel bands are not for show, but to hold up the mine roof. The water flowing down the tunnel towards the cages is authentic, apart from the fact that it now flows down a channel rather than over the miners' feet. In 2005, the Big Pit National Coal Museum won the prestigious Gulbenkian Prize. The museum hired mining apprentices in 2011; after serving an apprenticeship, the trainees would then have the necessary qualifications to work in a mine. The tour guide uniform for big pit is a black t-shirt and orange jacket and trousers with high-vis stripes, or an orange jumpsuit also with black t-shirt. This is to ensure that all visitors have the highest chances of seeing where their tour guide is, due to the pitch black conditions when there is no light. The museum features a range of above ground attractions including a winding house, saw mill, pithead, baths. Visitors are also taken below ground to the pit bottom where they tour the mine workings. In 2000, the Blaenavon industrial area, including Big Pit National Coal Museum, was named a World Heritage Site by UNESCO. This was in recognition of the town's importance to the Industrial Revolution. Museum staff walked out in disputes over pay in 2014, 2015 and 2016. The Blaenavon Cheddar Company, a local cheese company, ages its Pwll Mawr (Big Pit) cheddar at the base of the Big Pit mine shaft. Safety The mine is covered by HM Inspectorate of Mines regulations, because it is still classed as a working pit. Visitors wear a plastic hard hat, safety lamp, and a battery on a waist belt which weighs . Visitors must also carry on their belt a rebreather, which in case of emergency will filter foul air for approximately one hour, giving a chance for survival and escape. Before taking the 50 minute underground tour below ground, contraband must be surrendered, such as anything containing a dry cell battery from watches to mobile phones. The dangers of the mine are real, the safety posters on the stages of Carbon Monoxide poisoning serve as museum pieces and as real reminders of the