For the following National Institute for Occupational Safety and Health (NIOSH) filter designations N stands for Not Resistant to oil;R stands for Resistant to oil;and P stands for oil Proof.

• 答：对经过NIOSH认证防颗粒物呼吸器过滤元件，N指不适合油性的颗粒物，R指可以抵抗油性的颗粒物，P指能够防油性颗粒物。