Time Weighted Average Calculation

The time weighted average TWA) is a measure of a worker's average exposure to a contaminant, over the length of a work shift. The OSHA permissible exposure limit (PEL) is a TWA, as is the TLV recommendations from the ACGIH. Modern sampling instruments will calculate the TWA but it is still important to understand the concept and do the calculations. The tutorial also includes information about adjusting the PEL (or other exposure limit) for work shifts exceeding eight hours. Material is from SAFM 3423 and SAFM 4423 Northeastern State University. The EHSM program at Northeastern has been identified as a Qualified Academic Program by the Board of Certified Safety Professionals. The presenter is Dr. Doug Martin. Dr. Martin earned his Ph.D. from Oklahoma State University and is a CSP. In addition Dr. Martin worked as a safety manager in the construction industry for 20 years. For more information about the EHSM program at Northeastern you may contact Dr. Martin at [email protected].