Mercury Vapour Monitoring Guide: Ensuring Safety and Compliance

Human Health Consequences of Exposure to Mercury Vapour

Mercury is a metal that occurs in a range of forms including elemental, organic and inorganic. It is notable for being the only liquid metal at room temperature and for its toxicity to humans. Due to its unique properties, mercury is historically and currently used for a wide range of applications including manufacturing, mining, refining and electrical infrastructure.

The many forms mercury can take means exposure can occur in a variety of ways. Mercury vapour is particularly hazardous in the workplace due to the potential for inhalation. This gaseous form of elemental mercury can be released into the air at room temperature and when inhaled can be extremely dangerous due to its ability to rapidly be transported from the lungs into the blood stream.

Common sources of exposure to mercury vapour in Australia include:

• Gold production – Mercury is naturally found in gold ore. During extraction of gold from the ore, mercury is released into the atmosphere due to the extremely high temperatures.
• Coal power generation – Similarly to gold extraction, the burning of coal releases naturally occurring mercury into the atmosphere due to the low boiling point of mercury.
• Manufacturing – Mercury is used as a component in many products such as thermometers, batteries, light bulbs and as a catalyst for certain manufacturing processes.
• Waste disposal and recycling – Due to the prevalence of mercury in commonly used products, particularly electronics, large amounts end up in landfill and recycling facilities, requiring stringent safety and control measures to ensure workers are not exposed to mercury vapour.

Inhaling mercury vapour can have acute health impacts, affecting the respiratory system, causing breathing difficulties, the digestive system with symptoms like vomiting and abdominal pain, and the central nervous system, leading to headaches and muscle weakness. Damage can be permanent and long-term exposure can also have neurological and psychiatric effects.

Regulation of Workplace Mercury Vapour Exposure in Australia

Regulation of mercury vapour exposure in Australia is primarily through the operation of the Workplace Exposure Standards (WES). Under the WES, workers must not be exposed to elemental mercury vapour at an 8-hour time-weighted average (TWA) of greater than 0.025 mg/m³ or 0.003 ppm. No short-term exposure limit (STEL) is applied to mercury in the WES.

According to the model Work Health and Safety Laws and Regulations, it is the responsibility of a person who conducts a business or undertaking (PCBU) to ensure no one in the workplace is exposed to levels of mercury vapour exceeding the exposure limit. Where workers may be exposed to mercury vapour, PCBUs must conduct air monitoring to ensure the exposure standard is not exceeded and implement appropriate risk management strategies to mitigate the hazard.

Monitoring Mercury Vapour in the Workplace

Mercury vapour can be monitored in several ways. For compliance with the Workplace Exposure Standards, air monitoring is required. This generally involves air sampling using a standard sampling train set up and the appropriate filters, worn in a worker’s breathing zone for the duration of a shift. Samples are then analysed in a laboratory so that specific substances can be identified and time-relative concentrations can be calculated.

Sometimes passive (AKA diffusive) sampling may be suitable. Whilst passive sampling does not use an air sampling pump, lab analysis of the sample provides a high level of data that can be used to conduct mercury exposure assessments. This type of sampling utilises diffusion, the sampler is worn by the worker in the breathing zone as they go about their regular tasks and collects mercury vapour throughout the day. However, passive samplers are specifically designed to sample particular substances. For example, SKC’s 520 Series Inorganic Mercury Passive Samplers are designed to only adsorb mercury vapour onto the sorbent.

Straightforward, Accurate Detection with Portable Mercury Analysers

Unlike air sampling methods, portable mercury analysers allow for real-time monitoring of mercury vapour. This means no lab analysis is required for accurate atmospheric mercury vapour concentration readings. Portable mercury analysers such as the Ion Science MVI (Mercury Vapour Indicator) provide continuous monitoring of mercury vapour ensuring workers can be aware of their level of exposure in real-time and have audible alarms to indicate when concentration thresholds have been surpassed. The MVI also does not saturate or require regenerating, eliminating instrument downtime and detecting mercury vapour in just 3 seconds.

Where specialised monitoring of mercury vapour is required, portable mercury analysers are ideal. However, if a workplace is concerned with a range of airborne contaminants and does not require real-time monitoring of mercury vapour, other air sampling methods may be more suitable.

Ion Science MVI Portable Mercury Vapour Indicator

Handheld instrument for rapid, accurate and continuous detection of mercury vapour.

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