Is it harmful to be breathing in paint removal that is being used in the house?

So my flatmates are renovating the house. There is paint all over the wood work and they have been putting down paint remover and leaving it over night. I had a slight head cold, was feeling better, and then the night they put it down I developed a cough, and now I feel worse. I don't know if it's just a coincidence or if the paint remover is affecting me. My flatmates seem to be fine. They also won't leave any windows open to let it ventilate. I am worried for my health and this will be continuing for the next few nights. Should I be worried?