Almost every aspect of the health of late eighteenth and early nineteenth-century child workers was affected by the unprecedented urban and industrial growth of the period. A tripling of the population in the century after 1750 was dwarfed by a quadrupling in the size of the major industrial and trading centres between 1800 and 1850. New forms of production in the industrial districts of the West Midlands, northern England and the central belt of Scotland drew increasing numbers of workers into growing manufacturing towns, exposing them to unfamiliar raw materials, industrial chemicals, pollution and an unfavourable urban disease environment. Technical innovations also brought new heavy industrial machinery which changed fundamentally the types of operations required in industrial jobs and resulted in new and more violent forms of industrial injury. Of all the industrial sectors, cotton textiles experienced by far the most substantial rates of growth. Migrants to manufacturing towns were also attracted by new job opportunities and increasing industrial wages which rose by around 50 per cent over the first half of the nineteenth century. However, the overcrowding and poor sanitation which accompanied the growth of manufacturing centres meant that higher industrial wages did not normally translate into better health for urban families. Rapidly built housing of poor quality and the rudimentary sanitary infrastructure of towns such as Manchester and Leeds were swamped by the influx of migrant workers.