The Time Weighted Average (TWA) for the exposure to a chemical can be used when both the chemical concentration and time for exposure varies over time. It is usually averaged over 8 hours, which is used as the standard daily work shift.
time weighted average per time period =
= (((concentration at first level in ppm) * (number of hours exposed)) + ((concentration at second level in ppm) * (number of hours exposed)) + .... + ((concentration at nth level in ppm) * (number of hours exposed))) / (time period in hours)
To read more or access our algorithms and calculators, please log in or register.
