## Threshold Limit Values (TLV) for Silica Dust **Key Point:** The ACGIH (American Conference of Governmental Industrial Hygienists) TLV for respirable crystalline silica is **0.025 mg/m³** as an 8-hour time-weighted average (TWA). ### Context of Silica Exposure Respirable crystalline silica (RCS) is a Class 1 carcinogen and causes silicosis, a progressive fibrotic lung disease. The TLV is set at the lowest feasible level to minimize cancer and respiratory disease risk. ### Comparison with Other Standards | Standard | RCS TLV (mg/m³) | Notes | |----------|-----------------|-------| | ACGIH | 0.025 | Most stringent; based on carcinogenicity | | OSHA PEL | 0.05 | US Permissible Exposure Limit | | India (DGMS) | 2–3 | Older standard; less protective | **High-Yield:** ACGIH TLV of 0.025 mg/m³ is the reference standard in most modern occupational health curricula and is frequently tested in NEET PG PSM. **Clinical Pearl:** Workers in mining, foundries, sandblasting, and stone-cutting industries are at highest risk. Silicosis is irreversible and preventable only through exposure control.
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