If a person is working in an isolated area and there the only Halal food available for him are fruits and vegetables can he treat himself with non-Halal food as an act of desperation? For example, an engineer who works with an oil and gas company working on an oil platform? Can he be considered to be in an emergency situation? Under what circumstances are Muslims allowed to consume non-Halal food if that's the only choice available?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Any animal that was not slaughtered in a way acceptable by Islamic Shariah is considered Maytah. So, it is forbidden to consume unless in desperate situation that could cause death to the person if not eating from this meat. Allah Says (interpretation of meaning): {He has forbidden you only the Maytah (dead animals), and blood, and the flesh of swine, and that which is slaughtered as a sacrifice for others than Allâh (or has been slaughtered for idols, etc., on which Allâh's Name has not been mentioned while slaughtering). But if one is forced by necessity without willful disobedience nor transgressing due limits, then there is no sin on him. Truly, Allâh is Oft-Forgiving, Most Merciful.}[2:173].

As long as there are fruits and vegetables, then there is no need to eat meat that is not Halal, and any person who eats from such meat is considered a transgressor of the limits of Allah.

Allah knows best.