Nitrogen(N2)

Helium(He)

Neon(Ne)

Hydrogen(H2)

Narcosis

Narcotic beyond about 100 fsw

Non-narcotic

Non-narcotic

Narcotic at great depth

Decompression

Good on short dives; slow to eliminate on long dives

Easily eliminated, builds up slowly on short dives

Fairly easy to but better than He on log dives; fast on short dives

Worse than helium or N2, biochemical deco plausible

BreatheAbility

difficult to breathe at depth

Can be breathed to 5000 fsw

Relatively easy to breathe

Better than Helium

Thermal Conductivity

Fair to good

Poor

Fair

Very Poor

Voice Distortion

Normal

Large distortion

Nearly normal

Large distortion

Cost &

Lowest cost

Moderate cost

High cost, Limited

Low cost

Availability

Readily available

Fairly available

availability

Readily available