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.
In most cases if you quit your job, you are not eligible for unemployment. If you think your company may be downsizing in the future it may be in your best interest to be asked to be laid off if you feel like losing your job is imminent. That way you can collect the weekly benefit while looking for a new job.