Liquid mercury exists in a liquid state at typical room temperatures. It continuously evaporates, even at ambient temperatures, forming an invisible and odorless vapor. Understanding this process is important due to the health risks associated with inhaling mercury vapor.
The Evaporation Process
Evaporation occurs when liquid molecules gain enough energy to escape the surface and become a gas. For mercury, this happens because it has a measurable vapor pressure at room temperature, meaning some atoms are always transitioning into a gaseous state.
This process is influenced by several factors. Increased temperature significantly accelerates evaporation, leading to more mercury vapor in the air. A larger exposed surface area also increases the evaporation rate. Air movement, such as ventilation, enhances evaporation by carrying away the vapor, preventing re-condensation.
Health Implications of Mercury Vapor
Inhaling mercury vapor poses a significant health concern because it is readily absorbed by the lungs, with approximately 80% entering the bloodstream. Once in the circulatory system, elemental mercury vapor can cross the blood-brain barrier, affecting the central nervous system. Symptoms of exposure vary depending on concentration and duration, from acute to chronic effects.
Acute exposure can lead to severe lung damage, including pneumonitis, and may cause headaches, fatigue, and gastrointestinal disturbances. Chronic exposure often manifests as neurological and psychological effects, including tremors, memory problems, irritability, mood swings, and insomnia. Kidney damage and neuromuscular changes, such as weakness and muscle twitching, are also possible. Children are particularly susceptible because their nervous systems are still developing, and the vapor tends to settle closer to the floor where children play. The odorless and colorless nature of mercury vapor means its presence cannot be detected without specialized equipment, underscoring the risk of undetected exposure.
Sources of Mercury Vapor Exposure
Many household items contain elemental mercury, which can become a source of vapor exposure if released. Common examples include older glass thermometers, barometers, and certain antique blood pressure cuffs. Fluorescent light bulbs, including CFLs, contain small amounts of mercury, which can be released if broken.
Older thermostats often utilize mercury tilt switches, posing a risk if damaged. While older dental amalgam fillings contain mercury, intact fillings generally pose minimal risk; however, chewing can increase localized vapor release. Beyond household items, industrial processes like manufacturing or mining can also be sources of mercury vapor.
Safe Handling and Spill Response
Proper handling and response to liquid mercury spills are important to minimize vapor exposure. If a mercury-containing item breaks, it is crucial to avoid actions that can spread the mercury or increase vaporization. Never use a vacuum cleaner, broom, or paintbrush to clean up spilled mercury, as this can break the mercury into smaller droplets, increase its surface area, and disperse the toxic vapor into the air, contaminating cleaning equipment.
For small spills, such as from a broken thermometer, ensure the area is well-ventilated by opening windows and closing doors to other parts of the house. Everyone not involved in cleanup, including children and pets, should leave the area. Wear disposable gloves and eye protection.
Carefully collect visible mercury beads using stiff paper or cardboard to push them together, or use an eyedropper to pick them up. Smaller droplets can be collected with sticky tape. Place all collected mercury, broken glass, and contaminated cleanup materials into a durable, airtight plastic container or a heavy-duty plastic bag, which should then be sealed and properly labeled.
Contaminated porous materials like carpet or upholstery should be carefully cut out and disposed of, as mercury can become embedded and continue to vaporize. Contact your local hazardous waste disposal service or health department for guidance on proper disposal, as mercury-containing waste is regulated. For larger spills, or if you are unsure how to proceed, it is always recommended to contact local authorities or a professional hazardous waste cleanup service. Preventing spills by storing mercury-containing items safely and pursuing mercury-free alternatives whenever possible are the most effective ways to avoid exposure.