Abstract: On May 11, 2010, Employee #1, a church maintenance worker, was removing pool paint from a baptistery (similar to a sunken tub), using a push broom and a chemical called Klean-Strip Premium Sprayable Stripper. Klean-Strip Premium Sprayable Stripper contained approximately 70 to 85 percent methylene chloride, 1 to 4 percent methanol, 1 to 5 percent isopropyl alcohol, 1 to 5 percent ethanol, and 1 to 5 percent 2-butoxyethanol in n-butyl ether. According to a police report, Witness #1 stated that Employee #1 had allowed the chemical to soak, from approximately 3:00 p.m. to 3:30 p.m. At approximately 4:00 p.m., Witness #1 left the church, and that was the last time he saw Employee #1. At approximately 9:20 p.m., Witness #2 discovered Employee #1 unconscious, when she was walking around the facility prior to locking it up for the evening. Employee #1 was, therefore, killed between 4:30 p.m. and 9:20 p.m. Alhambra Police and Fire Departments responded to the accident. The Los Angeles County Coroner's Office removed Employee #1's body and the empty container of Klean-Strip Premium Sprayable Stripper. The Coroner's report indicated that Employee #1 was wearing gloves but was not wearing a respirator and eye protection. According to the Coroner's report, Employee #1 died of acute methylene chloride intoxication. The report indicated 10 percent saturation for carbon monoxide and volatiles, including methylene chloride, in Employee #1's blood. A reference material provided by the Coroner, a book entitled "Disposition of Toxic Drugs and Chemicals in Man, 8th Edition", cited a study (DiVincenzo et al. 1972), which estimated that 40 percent of an absorbed dose of dichloromethane (methylene chloride) was not eliminated as expired air. A portion of it was retained and metabolized to carbon monoxide. The book also cited studies that linked the level of exposure to the amount of carbon monoxide found in the blood. According to the Toxicological Profile for Methylene Chloride (US Department of Health and Human Services), COHb (carboxyhemoglobin) levels and presence of methylene chloride in the blood could be used as biomarkers, indicators of exposure to methylene chloride. However, COHb was not specific, meaning that other sources of carbon monoxide exposure required consideration (e.g., smoking, automobile exhaust). According to Witness #3, Employee #1 was not a smoker. The presence of methylene chloride in the blood could be used as a biomarker but only for recent exposures, because of its short plasma half life of approximately 40 minutes. Klean-Strip was mostly methylene chloride in content, which had the lowest PEL and was most volatile among all the other ingredients. Cal/OSHA regulated methylene chloride as a carcinogen. Because methylene chloride was potentially carcinogenic to humans, NIOSH recommended maintaining exposure to the lowest concentration feasible. The International Agency for Research on Cancer (IARC) classified it as a Group 2B compound, possibly carcinogenic to humans. Exposure limits included an OSHA Permissible Exposure Limit (PEL) of 25 parts per million (ppm), an OSHA Short Term Exposure Limit (STEL) of 125 ppm, and NIOSH Immediately Dangerous to Life and Health (IDLH) value of 2,300 ppm. Physical and chemical properties included a vapor pressure of 350 millimeters mercury (mmHg) (indication of volatility), density of 1.33 gram/milliliter (g/mL), and molecular weight of 84.9 grams/mole (g/mole) (heavier than air, which was approximately 29 g/mole). Greater molecular weight of methylene chloride than air created air stratification, which meant "methylene chloride concentration will be found at lower elevation than air." A second employee indicated that the doors leading to the baptistery and windows opening to the main sanctuary were closed, thereby creating an enclosed space. There were no fans to create cross ventilation. The employer was cited for failure to utilize engineering controls to prevent harmful exposure.