Objective The key positions in an auto parts manufacturing enterprise were studied, to explore the application of different occupational health risk assessments on chemical hazards in enterprise safety risk grading management.

Methods Occupational health risk assessment in these key positions was done with the exposure ratio method or the comprehensive index method, and then the risk levels were divided into four levels (A, B, C and D) combined with the enterprise safety risk grading management and control.

Results The results derived from exposure ratio method showed that the classification of risk level in the coating-primer inspection, the painting-topcoat inspection, the plastic surface refinishing was ranked as level-B (higher risk); the risk in the painting-varnish inspection and the manual refinishing in drying room was ranked as level-C (common risk); and the risk in the manual argon arc welding, the paint-mixing inspection, and the wastewater treatment was ranked as level-D (lower risk). The results derived from comprehensive index method showed that the classification of risk level in the wastewater treatment was ranked as level-B; the risk in the manual argon arc welding, the plastic surface refinishing and manual refinishing in drying room was ranked as level-C; and the risk in the other positions was ranked as level-D.

Conclusion It seems that the results derived from comprehensive index method were more realistic. However, this work can only be done by qualified profession, since the value assignment of certain parameter is subjective.