OnlineH2S Awareness Course

On completion of the online H2S Awareness training course learners will know;

• Why H2S is highly dangerous
• The risks to health associated with H₂S
• Understand where H₂S can be found
• The workplace exposure limits (WEL)
• Personal Safety Measures
• Team Safety Considerations

• Invisible – Hydrogen sulphide is a colourless gas
• Odorous  – Hydrogen sulphide is a flammable, colourless gas with a characteristic odour of rotten eggs.
• Density  – Hydrogen sulphide is heavier than air and may travel along the ground. It collects in low-lying and enclosed, poorly-ventilated areas such as basements, manholes, sewer lines, under- ground telephone vaults and manure pits.  Most deaths occur in confined spaces.
• Toxic  –  Gas burns and produces other toxic vapours and gases, that can cause death within a short space of time
• Explosive  –  H₂S has a lower explosive limit LEL of 4.3% and an upper explosive limit UEL of 46%

In the UK, two Workplace Exposure Limits (WELs) are defined for hydrogen sulphide (H₂S):

• Long-term exposure limit (8-hour TWA):5 ppm
• Short-term exposure limit (15-minute reference period):10 ppm

The table below outlines short-term symptoms associated with different H₂S concentrations:

• 0.01-1.5 ppm:
  • Rotten egg smell is first noticeable to some. The odour becomes more offensive at 3-5 ppm.
• 2-5 ppm:
  • Prolonged exposure may cause nausea, tearing of the eyes, headaches or loss of sleep. Airway problems in some asthma patients.

5ppm is the UK long-term exposure limit.  10ppm is the short-term (15 mins) exposure limit.

• 20 ppm:
  • Possible fatigue, loss of appetite, headache, irritability, poor memory, dizziness.
• 100 ppm:
  • Coughing, eye irritation, loss of smell after 2-15 minutes.  Altered breathing, drowsiness after 15-30 minutes. Throat irritation after 1 hour. Gradual increase in severity of symptoms over several hours. Death may occur after 48 hours.
• 200-300 ppm:
  • Marked conjunctivitis and respiratory tract irritation after 1 hour. Pulmonary edema may occur from prolonged exposure.
• 500-700 ppm:
  • Staggering, collapse in 5 minutes. Serious damage to the eyes in 30 minutes. Death after 30-60 minutes.
• 700-1000 ppm:
  • Rapid unconsciousness, “knockdown” or immediate collapse within 1 to 2 breaths, breathing stops, death within minutes.
• 1000-2000 ppm:
  • Nearly instant death

Hydrogen sulphide (H₂S) is found in various workplace environments, especially where organic matter decomposes.  For example, anaerobic digestion plants, slurry pits and offshore environments.

H₂S is also a by-product of several industrial processes, including petroleum refining, mining, tanning, wood pulp processing, rayon production, sugar-beet processing, and hot asphalt paving.

Hydrogen Sulphide gas is commonly found during the drilling and production of crude oil and natural gas, plus in wastewater treatment and utility facilities and sewers.

However, H₂S is a potential hazard in a wide range of industries and work environments, including, but not limited to:

• Animal fat and oil processing
• Asphalt storage
• Blast furnaces
• Breweries and fermentation processes
• Chemical production (including phosphate purification, hydrochloric acid purification, cellophane, rubber, plastics, soap, silk, photoengraving, glues, textile printing, etc)
• Clean-up activities of organic/sulphur containing slurry/sludge
• Coal gasification plants
• Coke ovens
• Farms and livestock operations
• Fertiliser production
• Fishing vessel holds
• Geothermal plants and utilities
• Landfills of municipal/farm/organic waste
• Metal processing
• Oil and gas (including crude oil refineries, handling plants and pipelines)
• Pulp and paper production
• Sewage treatment plants
• Slaughterhouses and rendering plants
• Sugar production
• Sulphur and hydrogen sulphide production
• Tanneries
• Waste treatment operations