Swanscombe is a small town in the District of Dartford in Kent, England. It is located east of Dartford and north-west of Gravesend, in the civil parish of Swanscombe and Greenhithe. At the 2001 UK census, the Swanscombe electoral ward had a population of 6,418. Swanscombe was important in the early history of concrete. The initial cement manufacturing works near Swanscombe were opened at Northfleet by James Parker, around 1792, making "Roman cement" from cement stone brought from the Isle of Sheppey. James Frost opened up a works at Swanscombe in 1825, making use of chalk from Galley Hill, having actually patented a new concrete called British Cement. The Swanscombe plant was ultimately obtained by John Bazley White & Co, which became the biggest component of Blue Circle Industries when it developed in 1900. It lastly closed down in 1990. In between 1840 and 1930 it was the largest concrete plant in Britain. By 1882 a number of concrete producers were running throughout the north Kent region, but the resulting dirt pollution drove individuals of Swanscombe to take legal action against the local concrete works. Regardless of different technological developments, the problem continued into the 1950s, with telegraph lines over an inch thick in white dust. Modern concrete kilns in Kent using smokeshafts 170 m (550 feet) in elevation are currently claimed to be the cleanest in the world. Nonetheless, the adjoining Medway towns are reported to be the most contaminated occupied location in the UK, as well as the concrete market contributes to acid rain in Scandinavia.