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Table 3 Severity of hazard criteria and scoring of chemicals

From: A screening tool to prioritize public health risk associated with accidental or deliberate release of chemicals into the atmosphere

Inhalational toxicity

    Flammability

    Reactivity

AEGL-3 or PAC-3 (mg/m3) for 60 min exposure

Toxicity score

NFPA flammability criteria*

NFPA score

NFPA reactivity criteria*

NFPA score

≤1

4

Flammable gas or cryogenic material

4

Materials with instantaneous power density (IPD) of 1000 W/mL or greater @ 250°C; sensitive to localized thermal or mechanical shock at normal temperature and pressure

4

Liquid with flash point (FP) below 22.8°C and boiling point (BP) below 37°C

  

Materials that spontaneously ignite when exposed to air

   

>1, ≤10

3

Liquids with FP below 22.8°C and BP at or above 37.8°C; or FP at or above 22.8°C and below 37.8°C

3

Materials with IPD at or above 100 W/mL and below 1000 W/mL @ 250°C; sensitive to thermal or mechanical shock at elevated temperature and pressure

3

>10, ≤100

2

Liquids with FP at or above 37.8°C and below 93.4°C

2

Materials with IPD at or above 10 W/mL and below 100 W/mL @ 250°C

2

>100, ≤1000

1

Liquids, solids, semi-solids with FP above 93.4°C

1

Materials with IPD at or above 0.01 W/mL and below 10 W/mL @ 250°C

1

>1000

0

If assigned 0 by NFPA

0

Materials with IPD below 0.01 W/mL @ 250°C

0

  1. * See NFPA 704 for complete listing of criteria [30].