Coal gas
Coal gas public street lighting systems were introduced in Montreal in 1838, in Toronto in 1841 and in Halifax in 1850. Coal gasification plants were built in these cities and others to provide the gas for the lighting systems. Most remained in operation until the 1950s when they were phased out due to a loss of demand in favour of the more practical and inexpensive natural gas. The decommissioning of these sites was often problematic due to the accumulation of toxic coal tar in the ground.