Objective To assess the risk of hearing loss caused by occupational noise exposure in workers in an automobile manufacturing plant in Tianjin, China, and to perform risk management. Methods Occupational health field investigation and noise exposure measurements were conducted from July to December 2023, and physical examination data were collected. ISO 1999:2013(E) Acoustics-Estimation of Noise-Induced Hearing Loss and WS/T 754-2016 ^“Guidelines for Risk Management of Occupational Disease Hazards Caused by Noise^” were used to predict the risk of high-frequency hearing loss and occupational noise induced deafness for operational workers and make a risk classification. Results The noise intensity of each workshop was 79.4 to 95.5 dB(A), and the maximum noise intensity of welding and stamping exceeded the standard. The results of the assessment showed that the noise level remained unchanged, and the risk of HFHL and ONID in workers increased as the predicted age and length of service increased. It was predicted that after the age of 40, the maximum risk of hearing loss in welding workers would be high risk, and the risk of stamping workers would be at higher risk, suggesting that welding and stamping were the key control posts of noise hazards in the enterprise. The N50 prediction values of permanent hearing threshold displacement caused by potential noise at all frequencies for final assembly and painting workers were lower than the measured values. Conclusion The consequences of hearing loss for workers in the welding and stamping shop noise operations at this automobile manufacturing plant are relatively serious and require risk management.

Objective: To investigate the relationship between urinary monohydroxylated metabolites of hydroxyl polycyclic aromatic hydrocarbons (OH-PAHs) and lung function, as well as the role of oxidative stress in these associations, so as to provide a scientific basis for air pollution control and policy formulation. Methods: A panel study was carried out among 45 young healthy adults. Four follow up surveys and health examinations were conducted from November 2017 to October 2018 to measure lung function parameters [forced vital capacity (FVC), second forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), FEV1/FVC, and forced expiratory flow between 25% and 75% vital capacity (FEF 25%~75% )], markers of exposure to 7OHPAHs [∑ 7OH PAHs], and markers of oxidative stress[8 hydroxy 2 deoxyguanosine (8 OHdG) and 8 isoprostaglandin F 2α (8 iso PGF 2α )]. The relationship between urinary PAH metabolites and lung function was quantified by linear mixed effects models. Mediation analysis was performed to assess the role of oxidative stress in the relationship between OH PAHs and lung function. Results: The median values of FVC, FEV1, FEVI/FVC, PEF, and FEF 25%-75% were 4.37 L, 3.58 L, 83.00%, 4.38 L/s, and 3.32 L/s, respectively. The results showed that each 1 unit increase in log transformed value of 2 Hydroxyfluorene (2 OHFlu) was associated with a 5.05% decrease ( β %=-5.05%，95% CI =-8.85%--1.09%) in FVC, 4.15% decrease ( β %=-4.15%，95% CI =-7.94%- -0.22% ) in FEV1 and 5.87% decrease ( β %=-5.87%，95% CI =-11.35%--0.05%) in FEF 25%-75% , respectively. Each 1 unit increase in log transformed values of 2 OHFlu and 9 Phenanthrol (9 OHPhe) was associated with a 7.03% decrease ( β %=-7.03%，95% CI =-12.60%--1.11%) and a 7.08% decrease ( β%=-7.08%，95% CI =-13.50%--0.17%) in PEF, respectively. Additionally, urinary ∑ 7OH PAHs had a positive correlation with the levels of urinary 8 OHdG and 8 iso PGF 2α ( r =0.64, 0.69, P <0.01). Meanwhile, the levels of 8 OHdG mediated 17.06% and 15.71% of the association between 2 OHFlu with FVC and FEV1. Conclusion The finding reveales a negative relationship between urinary OH PAHs and lung function among young healthy adults. The 8 OHdG plays a mediated role in the correlation of 2 OHFlu with FVC and FEV1. Active relevant policies are needed to control air pollution and maintain the healthy living conditions of young people.