What means the STEL and the TWA ?

STEL and TWA are acronyms related to occupational health and safety, specifically in the context of monitoring and controlling exposure to hazardous substances in the workplace. These terms are often used in the field of industrial hygiene and occupational health. Here’s what they stand for:

 

STEL: Short-Term Exposure Limit

The STEL represents the maximum concentration of a substance to which workers can be exposed over a short period, typically 15 minutes, without suffering adverse effects. It is designed to prevent acute health effects that can occur from brief but high-level exposures.
TWA: Time-Weighted Average

The TWA is a measure of the average exposure to a substance over a specified period, usually an 8-hour workday. It is calculated by averaging the exposure levels over different time intervals. The TWA is intended to address the potential long-term health effects of continuous or regular exposure to a substance.

These exposure limits are established by occupational health and safety organizations and are crucial for protecting workers from the harmful effects of various chemicals and substances commonly found in the workplace. Employers use these limits as guidelines to implement measures that ensure a safe working environment, such as the use of personal protective equipment, ventilation systems, and other engineering controls.