What Does Dose Mean?
Dose, with regard to workplace hearing conversation, refers to a measurement used to calculate the amount of noise a worker is exposed to over a specified period of time.
The noise dose for a worker is calculated using both the noise level in the employee's work environment and the duration of his or her exposure. This is because a person's hearing may be damaged by either a brief exposure to a very loud noise, or a longer exposure to noise at a lower decibel level. For instance, it may take two hours of exposure for hearing damage to occur at 91 decibels, but only 15 minutes of exposure at 100 decibels.
A worker's dose is expressed as a percentage of the permissible eight hour time-weighted-average exposure (TWA). For example, an 8-hour exposure to 90 decibels is considered a 100% dose. If the worker were exposed to 90 decibels for only four hours, the dose would be 50%.
Because sound levels usually vary of the course of a work day, several individual calculations may need to be combined to determine the individual's dose.