Table 2.

Levels and values of assessment standards.

Risk Grades		Range of CR	Acceptability
Grade I	Extremely low risk	<10−6	Completely accept
Grade II	Low risk	[10−6, 10−5)	Do not mind about the risk
Grade III	Low-medium risk	[10−5, 5 × 10−5)	Care about the risk
Grade IV	Medium risk	[5 × 10−5, 10−4)	Care about the risk and willing to invest
Grade V	High risk	>10−4	Pay attention to the risk and take action to solve it