time-weighted average

time-weighted average

[¦tīm ‚wād·əd ′av·rij]
(science technology)
The average exposure to a contaminant or condition (such as noise) to which workers may be exposed without adverse effect over a period such as in an 8-hour day or 40-hour week. Abbreviated TWA.
References in periodicals archive ?
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 of
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.
Time-weighted average 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 final rule establishes a permissible exposure limit (PEL) for respirable crystalline silica of 50 micrograms as an eighthour time-weighted average that was opposed by industry as unnecessary, not feasible, and not supported by scientific evidence.
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).
The purpose is to determine if an employee is affected by work-related hearing loss as a result of possible noise exposure in those work environments found to exceed the Action Level threshold of an 8-hour time-weighted average of 85 decibels measured on the A-scale.