Final answer:
The primary step in caring for a severe burn with white, dry, and leathery skin is to decontaminate by flushing the affected area to remove the chemical and reduce further skin damage.
Step-by-step explanation:
The first step in the care of a severe burn to both lower legs, where the affected skin is white, dry, and leathery, with skin peeling away, would be to decontaminate with flushing. This immediate action reduces the contact time of the chemical with the skin and reduces further skin damage. After decontamination, assessing the burn severity and preventing shock are crucial but initial flushing to remove the chemical is the primary concern. It is important to act quickly and cautiously, ensuring not to exacerbate the injury.