Cesspits were introduced to Europe in the 16th century, at a time when urban populations were growing at a faster rate than in the past. The added burden of waste volume began overloading urban street gutters, where chamber pots were emptied each day. There was no regulation of cesspit construction until the 18th century, when a need to address sanitation and safety concerns became apparent. Cesspits were cleaned out by tradesmen known in the UK as gongfermors using shovels and horse-drawn wagons. Cesspools were cleaned only at night, to reduce the smell and annoyance to the public. The typical cesspit was cleaned out once every 8 to 10 years. Fermentation of the solid waste collecting in cesspits, however, resulted in dangerous infections and gases that sometimes asphyxiated cesspit cleaners. Cesspits began to be cleaned out more regularly, but strict regulations for cesspit construction and ventilation were not introduced until the 1800s.