Respirator selection · particulate
Respirable crystalline silica respirator selectionSiO2
Mining, quarrying, foundries, abrasive/sand blasting, concrete and masonry cutting/grinding, tunneling, brick and refractory work, and engineered-stone/natural-stone countertop fabrication (a major modern silicosis source).
OSHA standard: 29 CFR 1910.1053 (general industry & maritime); 29 CFR 1926.1153 (construction)
These are federal OSHA limits. The PEL shown is the federal OSHA value. About two dozen states run their own OSHA-approved plans, and some — notably California (Cal/OSHA) — enforce lower or additional exposure limits. If you work under a state plan, check your state's PEL and enter it as a custom limit in the calculator.
Particulate hazard. Measured in mg/m³ and captured by N/R/P particulate filters — not gas/vapor cartridges. Respirable solid mineral particulate, non-oil aerosol - N/R/P series all technically acceptable; N-series (e.g., N95) is the minimum, but N100/P100 (HEPA-level) is strongly recommended because quartz is a carcinogen and blasting/cutting generate very high concentrations. Select filter/respirator by assigned protection factor for the measured airborne level. See the cartridge & filter guide.
Calculator for Respirable crystalline silica
Result
Enter a concentration and an exposure limit to see the
compliant respirators and their Maximum Use Concentration.
Hazard ratio = concentration ÷ OEL · Minimum APF must meet or exceed it · MUC = APF × OEL (capped at IDLH). Source: OSHA 29 CFR 1910.134(d)(3)(i)(A), Table 1 — Assigned Protection Factors. Last verified 2026-07-16.
Maximum use concentration for Respirable crystalline silica by respirator
MUC = APF × the OSHA PEL (0.05 mg/m3), capped at the IDLH (50 mg/m3). Use this as a reference for the highest concentration each respirator class may be used at.
| Respirator | APF | MUC (mg/m3) |
|---|---|---|
| Air-Purifying Respirator · Quarter mask | 5 | 0.25 |
| Air-Purifying Respirator · Half mask | 10 | 0.5 |
| Supplied-Air Respirator (Airline) · Half mask · Demand | 10 | 0.5 |
| Self-Contained Breathing Apparatus · Half mask · Demand | 10 | 0.5 |
| Powered Air-Purifying Respirator · Helmet / hood | 25 | 1.25 |
| Powered Air-Purifying Respirator · Loose-fitting facepiece | 25 | 1.25 |
| Supplied-Air Respirator (Airline) · Helmet / hood · Continuous flow | 25 | 1.25 |
| Supplied-Air Respirator (Airline) · Loose-fitting facepiece · Continuous flow | 25 | 1.25 |
| Air-Purifying Respirator · Full facepiece | 50 | 2.5 |
| Powered Air-Purifying Respirator · Half mask | 50 | 2.5 |
| Supplied-Air Respirator (Airline) · Full facepiece · Demand | 50 | 2.5 |
| Supplied-Air Respirator (Airline) · Half mask · Continuous flow | 50 | 2.5 |
| Supplied-Air Respirator (Airline) · Half mask · Pressure-demand / positive-pressure | 50 | 2.5 |
| Self-Contained Breathing Apparatus · Full facepiece · Demand | 50 | 2.5 |
| Powered Air-Purifying Respirator · Full facepiece | 1,000 | 50 |
| Supplied-Air Respirator (Airline) · Full facepiece · Continuous flow | 1,000 | 50 |
| Supplied-Air Respirator (Airline) · Full facepiece · Pressure-demand / positive-pressure | 1,000 | 50 |
| Self-Contained Breathing Apparatus · Full facepiece · Pressure-demand / positive-pressure | 10,000 | 50IDLH |
Notes
The current enforceable PEL is the 0.05 mg/m3 (50 ug/m3) 8-hr TWA under 1910.1053, which replaced the old formula limits in Table Z-3. IDLH 50 mg/m3 applies to quartz; cristobalite and tridymite have a lower 25 mg/m3 IDLH. Reference-only, not a substitute for a formal exposure assessment.
Sources
- https://www.cdc.gov/niosh/npg/npgd0684.html
- https://www.cdc.gov/niosh/idlh/14808607.html
- https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1053
Data confidence: high. Values are cited from OSHA and NIOSH but should be verified against the current source and a qualified professional before use. See how this works.