How is Respirator Type & Filter being determined?
If the exposure level for your work activity is above the occupational exposure limit (0.05 mg/m3) and you are unable to reduce it below 0.05 mg/m3 with other controls, then you will need to use respirators to reduce exposure. The respirator that is recommended will provide the required protection factor to reduce exposure below the exposure limit. For example, if the estimated exposure is 9 times higher than 0.05 mg/m3 (.05 x 9 = 0.45mg/m3) then a respirator with a protection factor of 10 will reduce your exposure by 10 times to 0.005 mg/m3, which is below 0.05 mg/m3 (0.45 mg/m3).
For related information, see Silica Control Tool Personal Protective Equipment (PPE) Respiratory Protective Equipment (RPE)