To identify the main chemical occupational hazard factors and their exposure levels associated with condensate oil in natural gas exploitation, and to explore occupational health risk assessment methods for chemical hazards in this industry, so as to provide a basis for accurately preventing occupational hazards and protecting the health of occupational populations.

Based on occupational health surveys, condensate oil component analysis and continuous monitoring of chemical occupational hazards, the occupational health risks of condensate oil exposure in natural gas exploitation were assessed using the comprehensive index method, ICMM quantitative assessment method and occupational hazard risk index method.

The main occupational hazard factors of condensate oil in natural gas exploitation were benzene, toluene, xylene, n-hexane and cyclohexane. Their time-weighted average concentrations (C_TWA) ranged within 1%-50% of the occupational exposure limits (OELs). Among the 10 gas production well stations, only xylene concentration showed statistical significance (P<0.001), while concentrations of the other four chemical toxicants were generally consistent (P>0.05). Short-term exposure concentrations (C_STEL) of all five typical chemical toxicants were detected in the gas field water treatment station, with generally consistent concentrations (P>0.05). Analysis of occupational health risk levels showed that according to the comprehensive index method, benzene was rated as extremely high risk in both gas production stations and gas field water treatment stations, toluene, n-hexane and cyclohexane as high risk, and xylene as medium risk. According to the occupational hazard risk index method, benzene was moderate risk in the gas field water treatment station and mild risk in gas production stations, while all other factors were assessed as no risk. In the ICMM quantitative assessment method, only benzene in the gas field water treatment station was rated as intolerable risk, and all other factors were rated as tolerable risk. The Kruskal-Wallis test showed significant differences in the rating distributions among the three methods (P<0.05), indicating that different assessment systems varied in their ability to discriminate risk levels of hazardous factors.

Benzene, toluene, xylene, n-hexane and cyclohexane should be the key occupational hazards concerned in condensate oil exposure in the natural gas exploitation industry. The improved ICMM quantitative assessment is a suitable method for occupational health risk assessment of condensate oil in natural gas exploitation.