Abstract: Occupational exposure limits for hazardous agents in the workplace—Part 1: Chemical hazardous agents (GBZ 2.1—2019) has been implemented since April 1, 2020. The document redefines the evaluation of occupational exposure by introducing a "reduction factor" to adjust the occupational exposure limits of chemical hazardous agents for long working hour systems to ensure a protection level reasonable for the workers and equivalent to conventional occupational exposure limits. This paper discussed common problems encountered in the context of using this adjustment strategy, such as the adjustment being unable to cover all working hours, and the adjustment of values of terms associated with occupational exposure limits. Corresponding solutions were proposed. Working cycle and average exposure time of each working cycle were introduced to evaluate the actual working hours of workers. Regarding involved terms, adjustments of their corresponding values were clarified according to their definitions and application scenarios. Examples were provided for occupational health service providers so that their occupational health practices could be carried out in a more scientific and reasonable manner.