Toxicology and TLV Calculation

Calculating Combined TLV

• The combined TLV is calculated using the formula: C1/T1 + C2/T2 + ... + Cn/Tn = Dose
• Where C is the concentration and T is the threshold limit value
• If Dose is greater than 1, the TLV for the mixture has been exceeded

Toxic Substances

• Median Lethal Dose (LD 50) is the dose of a toxic substance that would be fatal for 50% of a test population
• Median Lethal Concentration (LC 50) is the concentration of a toxic substance that would be fatal for 50% of a test population
• Immediately Dangerous to Life and Health (IDLH) refers to a condition posing immediate danger to life or health

Measuring Concentrations

• Airborne particulate concentrations are measured in milligrams per cubic meter of air (mg/m3)
• Gaseous concentrations are measured in parts per million or % by volume

Explosive Limits and Relative Density

• Lower Explosive Limit (LEL) is the minimum concentration of a gas or vapor that will ignite when exposed to an ignition source
• Upper Explosive Limit (UEL) is the maximum concentration of a gas or vapor that will ignite when exposed to an ignition source
• Relative density (vapour density or specific gravity) is the ratio of the density of a substance to the density of a standard substance

pH Scale

• pH scale measures a substance's acidity or alkalinity
• pH scale ranges from 0 to 14
• pH below 7 indicates acidity, pH above 7 indicates basicity or alkalinity, and pH 7 indicates neutrality

Mine Rescue

• Mine rescue teams have specific responsibilities, including controlling the scene, ensuring safety, and providing first aid
• Decision-making processes involve controlling the scene, ensuring safety, and assisting with casualty extrication and first aid
• Response elements include preparation, method of alert, establishing communication, safe travel, and arrival at the scene

Size Up

• Size up is a systematic process of gathering information and situational evaluation that continues throughout the operation
• Size up involves four parts: information gathered from the initial call, details observed en route, details observed at the scene, and ongoing evaluation

Ice Rescue

• Clear blue lake-ice is considered the strongest form of ice
• Slush ice (white hue) is weaker than clear blue lake-ice
• Cracks in ice may affect its ability to support a load
• The speed limit on ice roads is 25 km/h for a loaded vehicle and 35 km/h for an empty vehicle