Association between personal attenuation rating with types of earplugs and noise exposure levels in a textile factory in China.

Objective: To investigate the effects of earplug type and noise exposure level on textile workers' personal attenuation rating (PAR).

Design: Initial and follow-up visits were conducted at a 17-month interval. At each visit, a baseline HPD fit test was performed using either a 3M foam or pre-molded earplug, as chosen by the workers. Workers who failed to meet targeted levels were trained and retested. Once they failed again, the other earplug was selected, and training was provided until they achieved the PAR target.

Study sample: 192 textile workers into three noise exposure level groups (low, medium, high).

Results: The median baseline PAR was 10 dB at the initial visits and 13 dB at the follow-up visits, and obtained by foam earplug users was 20 dB, which was higher than that obtained by pre-molded earplug users [12 dB (95% CI, 10-15 dB)]. The highest median baseline PAR was obtained by the high noise level group, followed by the median and low noise level groups. Training significantly increased the PAR.

Conclusions: Multiple types of earplugs need to be offered to workers to deal with individual differences in attenuation, preferences, and exposure levels. Training and stricter compliance policies can improve HPD use and fitting, contributing to better hearing health.