The large number of factories in Manchester caused a considerable amount of pollution. Alexis de Tocqueville was a French aristocrat who visited the city in 1835. "A sort of black smoke covers the city. The sun seen through it is a disc without rays. Under this half daylight 300,000 human beings are ceaselessly at work"
Reference:
https://spartacus-educational.com/Industrial_Towns.htm (accessed 28Oct2020)