IEC 60079-10-1 edition 2.0, the global standard for hazardous area classification, was newly revised in 2015. There are many differences compared to the previous edition 1.0 version, first released in 2008, so it has caused confusion in the industry. In case of edition 1.0, the hazardous area extent can be derived through the mathematical formula, but in case of edition 2.0, there was the problem that the exact hazardous area extent was not known because of the mathematical formula of the plot for applying the hazardous area extent was not presented. In this study, we converted the plot introduced in edition 2.0 to CAD format and derived the plot as the mathematical equations. Through this, we suggest the hazardous area extent formula of three states (heavy gas, diffusive, jet). As the IEC committee did not provide the mathematical formula of the hazardous area extent according to the release characteristic, it is impossible to apply the exact hazardous area extent. In this study, a mathematical approach was derived for the plot introduced in edition 2.0, which can reduce the confusion of the applying hazardous area extent.

This study was conducted to evaluate the health risk of workers exposed to phenyl glycidyl ether to prevent themfrom developing occupational diseases. The workplaces that coat floor with epoxy were selected and the sampleswere collected and analyzed with NIOSH 1619 Method. Unit risk was calculated according to the animalcarcinogenicity study. Excess cancer risk was also calculated by multiplying unit risk by exposure concentration.Monte Carlo simulation was performed to calculate the median, cumulative 90%, and cumulative 95% value.Phenyl glycidyl ether is a skin, eye irritator and can result in allergic reaction, nausea, intoxication. Unit risk wascalculated as 0.04 (mg/m³)-¹ based on the tumor incidence in rats. Geometric mean and geometric standarddeviation was also calculated as 0.112 ppm and 0.223, respectively by the workplace environment measurements.The median, cumulative 90%, and cumulative 95% value of excess cancer risk were calculated as 0.0244, 0.1328,0.1596, respectively. Not only cumulative 90% and cumulative 95% value but also the median of excess cancerrisk is much higher than 1×10-⁴ by the risk characterization, so there is a possibility of carcinogenesis to workers.Therefore, supervisors or managers of each workplace have to keep doing the risk management of their workplacesfor workers to reduce exposure to phenyl glycidyl ether.