Is it permissible for my husband to break his fast in Ramadan due to his strenuous 12-hour daily work, which causes him dizziness and headaches, thus affecting his performance in his critical job as a pharmacist, knowing that the travel distance does not permit breaking the fast?

Fasting is an established pillar [of Islam]; it is not permissible to break it except for a legitimate Shar'i excuse such as illness or travel. It is permissible for a thirsty person to pour water over their head and rinse their mouth to cool down. If the thirst will cause severe harm or perishment, then it is permissible to break the fast and make it up later. Work should not be a cause for hardship, and a Muslim must balance their religious obligations with their worldly affairs. If work conflicts with fasting, they should take leave, seek another job, or postpone strenuous work until night. "And whoever fears Allah - He will make for him a way out And provide for him from where he does not expect." (Quran 65:2-3). If one cannot find work that combines both matters, and is compelled to do strenuous work, they should fast until they feel hardship, then break their fast to the extent of the need, then refrain [from eating and drinking] for the rest of the day and make it up later.