Kailem Donovan, 37, from Middlesborough, England, works on oil rigs in the North and Baltic seas. Donovan works 12-hour shifts but gets three weeks of holiday every three weeks working on the rig.

NEW ORLEANS — Fifteen years after the Deepwater Horizon oil rig exploded off the Gulf Coast, killing 11 and sending 134 million gallons of crude gushing into the ocean, the effects of the nation ...