Without knowing when in the story this question is asking about or exactly which conditions that the question refers to, it is harder to answer the question.
Let's start with factory conditions. They are horrible when Lyddie gets hired, and they get worse from there as the factory owners speed up production and push the girls to their breaking points.
Creation! What a noise! Clatter and clack, great shuddering moans, groans, creaks, and rattles. The shrieks and whistles of huge leather belts on wheels.
The mills are loud, and hearing damage is a concern; however, the hearing damage is not one of the health hazards that the author highlights. Impact injuries from the machines and their various moving parts was a real concern, and that is how Lyddie gets physically injured at one point.
Tuberculosis was common, and it was spread through what Diana calls the "kiss of death." When a weaver needs to feed the thread through the final part of the shuttle, the weaver places her mouth on the end of the shuttle and sucks out the end of the weft thread. This is a "kiss of death" because a single weaver with tuberculosis could contaminate multiple shuttles by doing nothing more than placing her mouth on the shuttle.
"We call it the kiss of death," she shouted, smiling wryly to soften the words.
Another lung disease called byssinosis could also be developed by the workers. It is caused by exposure to dust from cotton, and the dust collects in the bronchioles and obstructs air flow into the lungs and alveoli. Symptomatically, the disease resembles asthma and chronic obstructive pulmonary disease.
The dangerous working conditions are stressful, and that stress is compounded by a lack of good rest. The girls work long hours, and they do no get adequate time to "decompress" and rid the body of stress loads. The girls work in close quarters, and they live in close quarters, so mental health is a struggle for Lyddie and her roommates. As the novel progresses, we see Lyddie and her roommates occasionally become short and frustrated with each other.
These moments increase in their frequency and intensity once the petition for better working conditions begins to seriously circulate and gain ground. Some of Lyddie's roommates fervently support signing the petition, because they feel the factories treat the workers as slaves. Lyddie strongly wants to believe that she isn't being treated as a slave, so she argues against the comparison as well as speaks against signing the document. Conditions will become physically and mentally straining enough that girls begin to leave.