Hydrogen Sulfide (H2S) is
colorless, highly toxic gas and has distinctive smell of rotten eggs.H2S occurs naturally in crude petroleum, natural
gas, sour condensate, sewage
sludge, volcanic gases, and
sulfur hot springs. It can also produce
from bacterial breakdown of organic matter and human and animal wastes.H2S
is heavier than air and may gathers in low areas such as sewers, pits, trenches, tunnels and
bottom of storage tanks or vessels.H2S is highly flammable at
concentrations between 4.3% to 46%.
Physical Properties
Colorless (invisible), highly flammable, highly
corrosive, irritant to eyes and respiratory system, strong odor of rotten eggs at
low concentrations, high concentrations may have no odor; rapidly paralyzes the
sense of smell, heavier than air and may settle in to low lying areas, highly
reactive in the presence of acids or strong oxidizing agents, soluble in water.
H2S burns with a blue flame and producing sulfur dioxide (SO2) which is also a
toxic gas.
Health Effect of H2S
H2S
(ppm)
|
Health
Effects
|
<0.005
|
Smell threshold
|
10
|
Threshold limits value (TLV&TWA)
8hrs/day or 40 hours/week
|
20-100
|
Eye and Respiratory system irritation
,Headache, Nausea & Cough
|
100-150
|
Severe eye respiratory system irritation.
Some possibility of fluid accumulation in the lungs after several hours of
exposure.
|
150
|
Loss of smell, which can occur immediately.
|
200-300
|
Accumulation of fluid in lungs after 1-2
hours of exposure, severe headache and drowsiness.
|
300-500
|
May produce unconsciousness and death after
1-4 hours of exposure.
|
500-700
|
Dizziness, breathing difficulties after a
few minutes of exposure. Breathing will stop and death will result if not
rescued promptly. Requires immediate artificial resuscitation
|
700-1000
|
Rapidly fatal, death within a few minutes.
|
First Aid
Do Not Attempt to Rescue if
you are not trained or without Proper PPE.
- Remove the victim from gas to fresh air immediately.
- If the victim is
not breathing, applying mouth to mouth resuscitation at once.
- If H2S contacts eyes, wash eyes immediately with water
- Remove contaminated clothing and keep the victim warm.
- Call medical assistance
