 In the first half of the 19th century the population of London more than doubled, from a little under a million people in 1801 to almost two and a half million in 1851. Despite this rapid growth in population, the amount of land set aside for use as graveyards remained unchanged at approximately 300 acres (0.47 sq mi; 1.2 km2), spread across around 200 small sites. The difficulty of digging without disturbing existing graves led to bodies often simply being stacked on top of each other to fit the available space and covered with a layer of earth. In more crowded areas even relatively fresh graves had to be exhumed to free up space for new burials, their contents being unearthed and scattered to free up space. In some cases large pits were dug on existing burial grounds, unearthing the previous burials, and fresh corpses crammed into the available space. Intact material from burials was sold on a thriving market in second hand coffin furniture, coffin wood was burned as household fuel, and exhumed bones were shipped in bulk to the north of England to be sold as fertiliser. Decaying corpses contaminated the water supply and the city suffered regular epidemics of cholera, smallpox, measles and typhoid; in 1842 the mean working life of a London professional man was 30 years and of a London labourer just 17 years.
