Permissible Exposure Limit (PEL)
1.25
mg/m³
PEL = 10 / (% Quartz + 3)
Standard Assessment Mode
Regulatory Framework
Based on The Factories Act, 1948 - Second Schedule. Occupational exposure limits for crystalline silica.
Scientific Methodology & Examples
Factories Act (mppcm)
Limit = 10,600 / (% Quartz + 10)
Example: 20% Quartz → 353.33 mppcmTotal Dust (mg/m³)
Limit = 10 / (% Quartz + 3)
Example: 5% Quartz → 1.25 mg/m³Respirable Dust (mg/m³)
Limit = 10 / (% Respirable Quartz + 2)
Example: 5% Quartz → 1.43 mg/m³Mines (Respirable)
1.0 mg/m³ if Silica ≤ 5%, else 5 / % Silica
Example: 10% Silica → 0.50 mg/m³