Carbon Dioxide Effects and Concentration

Study Notes

Carbon dioxide (CO₂) increases in mine air due to breathing, open flames, explosions, blasting, and thermal water escape.
- Effects on humans:
  - Increases respiratory rate, with a 50% increase at 20,000 ppm, 100% increase at 30,000 ppm, and 300% increase at 50,000 ppm.
  - Can be survivable for only a few minutes at 100,000 ppm.

Properties:
- Colourless, odourless, tasteless gas
- Explosive range of 12.5%-74%
- Slightly soluble in water and not removed by water sprays
- Slightly lighter than air
How formed:
- Product of combustion in normal blasting operations and internal combustion engines
- Produced by mine fires, gas explosions, and burning of organic compounds in low-oxygen environments
Effects on humans:
- Reduces haemoglobin's capacity for carrying oxygen to tissues
- Symptoms:
  - No symptoms at 0-35 ppm
  - Flu-like symptoms at 36-200 ppm
  - Dizziness, drowsiness, vomiting at 201-800 ppm
  - Unconsciousness, brain damage, and death at 801+ ppm

Purpose:
- Ensure safety of workers and property in mine sites
- Respond to incidents and emergencies
Training and procedures:
- Basic equipment, procedures, and practices
- Hazard assessment and evaluation
- Formulating objectives and risk-based decision-making
- Selecting alternatives and taking appropriate action
- Analyzing results and adapting to changes

Toxic chemicals:
- Concentrations measured in parts per million (ppm)
- Examples to help visualize 1 ppm:
  - 1 metre step in 1,000 kilometers
  - 1 millilitre per 1,000 litres of liquid
  - 1 square centimetre in 100 square metres
  - 1 cent in 10,000 dollars
Threshold limit values (TLVs):
- Airborne concentrations of substances that most workers can be exposed to without adverse effect
- Categories:
  - TLV-Time Weighted Average (TLV-TWA) for normal 8-hour workday and 40-hour workweek
  - Concentration Equivalent (Ceq) formula for shifts longer than 8 hours and 40 hours

Properties:
- Heavy, greenish-yellow, non-flammable gas
- Odour similar to chlorine bleach
- Tasteless
How formed:
- Electrolysis of common salt and other chemical reactions
Uses:
- Treating potable water and milling processes
Effects on humans:
- Severe irritant to eyes, skin, and respiratory system (oedema)
Other information:
- Not flammable, but can react to cause fire or explosions with certain materials
- Requires specially trained workers to manage incidents