Allergies are the result of a hypersensitive immune system. The allergic immune system misidentifies an otherwise innocuous substance as harmful, and then attacks the substance with a ferocity far greater than required.
Laying off an employee is different from firing an employee. Firing means letting a worker go for any reason, whereas a layoff refers to an employment termination based on economics, usually involving more than one worker.
Paid time off is a bank of hours from which employees can draw. Employers credit additional hours to their employees banks, usually every pay period. Most US employers offer their workers 10 paid holidays, 2 weeks vacation, two personal days, and 8 sick leave days per year. Under a PTO plan, the employees would be credited with 30 days paid time off instead (10+10+2+8).