This is a really perceptive question that forces us to put the story into its historical context. You are right, Germinal is set during the time of French industrialization and the Industrial Revolution. While Germinal focuses on the conditions of workers in the mines of France, the English Industrial Revolution often focuses on the conditions of the workers in factories and workhouses.
In Germinal, the living conditions and the working conditions in Montsou are deplorable especially in regard to the actual mine called the Voreux (which literally means "voracious"). This is an apt title as the mine devours all who work there. It swallows humans whole and spits them out devoid of all light and joy and health. Note the similarity to the tone of the entire entity of Montsou:
On a pitch black, starless night, a solitary man was trudging along the main road from Marchiennes to Montsou, ten kilometers of cobblestones running straight as a die across the bare plain between fields of beet.
Of course, the setting and the mine aren't the real problem: the aristocracy is the problem. Namely, the board of directors is corrupt. The board takes the profits and lives off the poor people who work there.
This echoes the Industrial Revolution as a whole, but specifically in England where the conditions were just as bad in the workhouses and factories. One need only bring up images of Blake's "The Chimney Sweeper" from his Songs of Experience to conjure up appropriate images of the English Industrial Revolution.
When my mother died I was very young,
And my father sold me while yet my tongue
Could scarcely cry 'weep! 'weep! 'weep! 'weep!
So your chimneys I sweep, and in soot I sleep.
There's little Tom Dacre, who cried when his head,
That curled like a lamb's back, was shaved: so I said,
"Hush, Tom! never mind it, for when your head's bare,
You know that the soot cannot spoil your white hair."
The same desperation and the same desolation are described, but this time in the soot of England and, this time, destroying the youth of the nation. As a further comparison, one only need mention Dickens' Oliver Twist with Oliver feverishly working in a workhouse and, after being given a measly meal of watery gruel, being punished when asking for "more."
Using any of these works in comparison, we can see as readers that the Industrial Revolution was truly a time of ill health and despair both for France and for England (to say nothing of the horrible conditions of the Lowell Factory Girls in Lowell, Massachusetts in the USA)!