Is it permissible to remove the niqab due to shortness of breath resulting from severe anemia?

A woman is not permitted to uncover her face. Covering the face is obligatory, according to the preponderant opinion. It can be covered with a niqab, a ghitwah, or a bishah, provided that it is not transparent. Anemia has a cure, and the means of treatment must be pursued. The obligation to cover the face is waived in cases of necessity for work, and the extent of uncovering is determined by the necessity.