Background Occupational hazards in the workplace are often determined through on-site investigations and recognized hazards to determine monitoring items, and occupational health risk assessments are rarely carried out on the monitoring results.

Objective Based on the qualitative results of volatile organic compounds, to monitor 8 types of volatile organic compounds in workplace air, and conduct occupational health risk assessments for workstations with disqualified results.

Methods This study selected 29 enterprises from 12 key industries listed in the Work Plan for Monitoring Occupational Disease Hazards in Workplaces in Chongqing (2023) in 5 districts and counties of Chongqing. A total of 49 key workstations, including spray painting, glue brushing, glue adjustment, adhesion, printing, bonding, packing, oil film, feeding, material preparation,dispersion, and immersion, were selected for air sampling and chemical headspace treatment. The volatile organic compounds in the headspace were separated with a gas chromatography capillary column and sequentially entered into a mass spectrometer for detection. Qualitative analysis of each component was conducted using the National Institute of Technical Standards and Technology standard spectrum library and retention time. Based on the qualitative results, chemical hazards and related workstations were determined, then quantitative evaluation was conducted for key hazards in workplace air, and followed by occupational health risk assessment for the disqualified workstations using semi-quantitative exposure ratio.

Results One or more of the 8 key chemical hazards were positive in the 29 enterprises, among which xylene (89.7%) and toluene (86.2%) had the highest positive rates, followed by benzene (34.5%), 1,2-dichloroethane (31.0%), ethylbenzene (20.7%), n-hexane (10.3%), and trichloromethane (6.9%), and trichloroethylene was negative. In the quantitative evaluation for occupational hazards in workplace air, the highest positive rates of chemical hazards were xylene (70.6%) and ethylbenzene (83.3%), and the highest disqualification rate of chemical hazards was 1,2-dichloroethane (50.0%). Out of the 29 enterprises, 8 reported disqualified air key chemical hazards, mainly in the workstations of spray painting and immersion. One spray painting workstation reported 3 disqualified chemical hazards, and one spary painting workstation reported 2 disqualified chemical hazards. The risk level of 1,2-dichloroethane in the spary painting workstations of 3 enterprises was high. The joint risk of 2 enterprises with multiple disqualified chemical hazards was high.

Conclusion The positive rates of benzene derivatives and 1,2-dichloroethane in workplace chemicals are high in this study. The risk level of 1,2-dichloroethane in the spary painting workstations of 3 companies is high, and this substance needs special attention in future monitoring.