CHST Practice Test – Complete Exam Preparation

To determine the estimated exposure after using hearing protection, it's important to understand how the noise reduction rating (NRR) impacts the sound level reaching an individual. In this situation, employees are initially exposed to a noise level of 98 dBA for an 8-hour shift. When hearing protection with an NRR of 24 dBA is used, we subtract this rating from the original noise level to find the effective exposure level.

When calculating the effective noise level with hearing protection, the following formula is typically used:

Effective Noise Level = Original Noise Level - NRR

Applying the given data:

Effective Noise Level = 98 dBA - 24 dBA = 74 dBA

This shows that by using hearing protection with a 24 dBA NRR, the estimated exposure level is significantly reduced to 74 dBA. This is crucial for promoting hearing conservation and protecting employees from potential noise-induced hearing loss.

The other options do not accurately reflect the calculation based on the NRR and original noise level. The values of 90 dBA, 81 dBA, and 98 dBA do not consider the impact of the hearing protection and therefore do not represent the effective exposure level when adequate protection is used.