Lab Safety
Exposure Limits
Less Hazardous More Hazardous
High TLV or PEL Low TLV or PEL
| TLV or PEL (ppm)* | Relative Degree of Hazard |
| Less than 1 | Extreme |
| 1 to 10 | Extreme to High |
| 10 to 100 | High to Moderate |
| 100 to 1000 | Moderate |
| Greater than 1000 | Very Low |
*ppm = (mg/M3)(24.45)/MW
* Permissible Exposure Limits (PEL) - A legally enforceable exposure limit in air. It represents OSHAs 8-hour weighted average exposure limit for a substance.
* Threshold Limit Value (TLV) - Airborne concentrations of substances that represents conditions under which it is believed that nearly all workers may be exposed day after day with no adverse effect.
Page last modified May 10, 2010
