Meteorological conditions such as wind speed were taken into consideration when determining the need for active sampling. Passive samples made up approximately seventy percent (70%) of the personal exposure sample total and active samples made up the remaining thirty percent (30%). Passive and active sampling techniques were used for the collection of personal exposure samples. Following the development of plant/process specific exposure profiles SEGs were developed and their membership identified. The Project Director and Field Sampling Team Leader met with each plant's operations/engineering personnel and identified plant specific exposure profiles. Identify locations in the plant process where mercury may accumulate and increase the potential for personnel exposure (Natural Gas Sampling and Analysis Plan) 4.1 Personal Exposure Sampling and Analysis Methodology 4.1.1 Similar Exposure Groups Measure the impact of specific plant operation and maintenance events on the concentration of mercury in ambient air in surrounding areas (Ambient Air Sampling and Analysis Plan) 3. The sampling and analysis plans were designed to: 1.ĭetermine the time weighted average concentration of mercury in breathing zone air that gas operations personnel are exposed to during specific work tasks and processes (Personal Exposure Sampling and Analysis Plan) 2. These are classified as confined spaces, and access to them has to be tightly controlled. There may be some substantially enclosed areas which may have flammable, toxic or asphyxiating atmospheres which we cannot design out. Note that there are many substances which are both toxic and flammable, and both hazards should be considered simultaneously. Failing that, we can use engineering controls such as ventilation, avoidance of enclosure, controlling access to contaminated areas, and so on. If we identify excessive exposure to toxic chemicals in our design, we should first consider substituting the materials which produce toxic hazards. The HSE Publication EH40 gives exposure limits for a wide range of chemicals (see “Further Reading”). The short-term exposure limit (STEL) is the time-weighted average concentration of a substance over a 15 min period thought not to be injurious to health. The long-term exposure limit (LTEL) is the time-weighted average concentration of a substance over an 8-h period thought not to be injurious to health. Seán Moran, in An Applied Guide to Process and Plant Design, 2015 Toxic hazards