Scale

Severity

Detection

Frequency

Frequency/Indicator

10

Highly hazardous

Non-detectable

1 in 2

Very high

0.5

9

Hazardous

Very improvable

1 in 3

Very high

0.33

8

Very high

Improvable

1 in 8

High

0.125

7

High

Very low

1 in 20

High

0.05

6

Moderate

Low

1 in 80

Moderate

0.0125

5

Low

Moderate

1 in 400

Moderate

0.0025

4

Very low

Moderately high

1 in 2000

Low

0.0005

3

Minor

High

1 in 15,000

Low

6 × 10−5

2

Very minor

Very high

1 in 150,000

Very low

6 × 10−6

1

None

Highly detectable

1 in 1,500,000

Remote

6 × 10−7