Basic Qualifications

Substance Name :  Hydrogen
Formula :  H ₂
CAS Number :  1333-74-0
Physical Description :  Colorless, odorless gas.
Relative Gas Density : 0.07 (Clean air: 1.0)
Molecular Weight :  2.0 g/mol
Ppm Conversion :  1 ppm = 0.083 mg/m ³
Melting Point :  -259°C
Boiling Point :  -253°C
Flash Point :  — (Gas)
Auto-Ignition Point : 560°C
Hazard Type :  Flammable-Explosive, Asphyxiating

Exposure Limit Values ​​(For Toxic Gases)

Short Term (15 Minute Average, NIOSH STEL):  —
Long Term (10 Hour Average, NIOSH TWA):  —
Immediate Discontinuance (NIOSH IDLH):  —

Flammability (For Flammable Gases)

Lower Explosive Limit (LEL) :  4%
Upper Explosive Limit (UEL) :  75%

Hazard Details

> It is a highly flammable gas. If it reaches amounts exceeding 4% in the environment it is in, there is a risk of fire or explosion.
> Although it is not toxic, if it is found in high amounts in closed areas, it can reduce the oxygen content of the air and cause suffocation.

Sources:
National Institute for Occupational Safety and Health (NIOSH) Pocket Guide to Chemical Hazards
International Labor Organization (ILO) International Chemical Safety Cards ICSCs