OSHA dictates employers have a hearing conservation program if employees are exposed to an 8-hour time-weighted average
(TWA) at or above 85 dB (A), and then requires hearing protection be worn at or above a 90 dB (A) TWA.
The updated Respirable Crystalline Silica Standard for General Industry and Maritime standard establishes a new eight-hour time-weighted average
permissible exposure limit and action level, plus associated ancillary requirements.
In most instances, individual states adopted an exposure level of 5,000,000 particles per cubic foot (ppcf) of total dust (not only asbestos fibers) of air based on a time-weighted average
over an eight-hour work day.
Researchers typically interpret the time-weighted average
pressure (TWAP), number of yielding events, setting pressure, and final pressure from a single shield cycle [13,15-17,20].
Federal law requires employers to protect worker hearing whenever noise exposures are at or above an 8-hour time-weighted average
At each of the surveyed plants, the operation characteristics were monitored during the work shift to calculate the time-weighted average
heat level and the time-weighted average
metabolic rate to which each worker was exposed.
THM concentrations (micrograms per liter) were multiplied by individual water use and THM uptake factors [micrograms/(micrograms per liter)liter for consumption or micrograms/(micrograms per liter) min for showering/bathing] to estimate whole pregnancy and trimester-specific average THM uptake into blood (micrograms/day) for each activity (water consumption, showering, bathing).
The device tracks, calculates and displays three cumulative formaldehyde gas metrics: 8-hour TWA (Time-Weighted Average
), 1-hour average, and 15-minute STEL (Short-Term Exposure Limit).
The time at temperature histogram can be used to construct a time-weighted average
x-factor by simply proportionally weighting the number of hours per year at a given temperature with the associated x-factor for that temperature.
OSHA did extensive sound intensity testing and came up with a time-weighted average
of just over 86 decibels (dBA).