TWA

Definition

Time-Weighted Average (TWA) in air sampling refers to the average air concentration of contaminants during a particular sampling period.

Purpose

The purpose of TWA is to assess the exposure of individuals to airborne contaminants over a specific period, typically an 8-hour workday, to ensure compliance with occupational health and safety standards.

Examples of Use

1. Occupational Safety: Measuring workers' exposure to hazardous substances in industrial environments to ensure safety.
2. Environmental Monitoring: Assessing air quality over time to understand pollutant levels and health impacts.
3. Regulatory Compliance: Ensuring that workplaces meet regulatory standards for exposure to airborne contaminants.

Related Terms

• PEL (Permissible Exposure Limit): The maximum amount or concentration of a chemical that a worker can be exposed to under OSHA regulations.
• STEL (Short-Term Exposure Limit): The acceptable average exposure over a short period, usually 15 minutes.
• Threshold Limit Value (TLV): Guidelines for exposure limits to chemical substances and physical agents in the workplace.

Notes

• Calculation: TWA is calculated by averaging the concentration of contaminants over the specified period.
• Importance: Accurate TWA measurements are essential for protecting workers' health and ensuring a safe working environment.