As the main risk factor of hearing loss, noise in MSWLs is mainly generated by the large machineries
and can be even over 90 dB that much higher than OSHA noise standard 1910.95 (85
dB) [10]. The risk of developing hearing loss is considered to be low at noise exposures below
85 dB (8-hour time-weighted average), but increases significantly when exposures rise above
this level [11]. However, several studies have reported significantly increased risk of hearing
loss even if the noise exposures were lower than 85 dB, especially when the noise exposures
were combined with other occupational hazards that may also induce hearing loss [12–14]. In
addition, certain chemicals, such as xylene and toluene that could exist in MSWLs have been
reported to cause damage on the auditory system [15,16]. It is of importance to identify if the
MSWL workers have more risk to develop occupational hearing loss.
Here, we carried out a cross-sectional study to conduct environmental monitoring at
MSWL work sites, administrated audiometric testing and collected data through questionnaires
of MSWL workers, aiming to investigate the occupational hazards, including noise and
TVOCs, at MSWLs and evaluate the occupational hearing loss among MSWL workers.