Bouffant caps are always recommended in clean rooms.
A bouffant cap is a cap which completely covers the hair properly so it is preferred in clean rooms,because it is important to avoid loose hairs. They are usually made of polypropylene or some other non-woven material, with an elastic band around the rim to keep it tight around the head below the hairline.These are disposable types of caps.
Bouffant Caps or Bonnets look like shower caps and are designed to cover the hair to protect against dry particulates in nonhazardous environments.A 'bouffant cap' got its name because of its resemblance with hair style.(Which is characterized by hair piled high on the head and hanging down on the sides)
As they can be worn by any sex and over any hairstyle, bouffant caps are a popular and economical choice of workplace head covering.