Phosgene monitoring

Methods and iastmments that are used to monitor phosgene content ia air are well developed and have been reviewed (46—48). One detection iastmment is a porous tape that measures the concentration of phosgene ia air ia quantities as small as 6 ppb (49). Fourier transform ir spectrometry techniques have been developed to permit line and area monitoring ia the area around phosgene plants (50). 

Methods and instruments that are used to monitor phosgene content in air are well developed and have been reviewed (49-51). One detection instrument is... 

Monitoring Phosgene and Phosgene Substitutes Analytical Methods... 

Health and Safety. Remover formulas that are nonflammable may be used in any area that provides adequate ventilation. Most manufacturers recommend a use environment of 50—100 parts per million (ppm) time weighted average (TWA). The environment can be monitored with passive detection badges or by active air sampling and charcoal absorption tube analysis. The vapor of methylene chloride produces hydrogen chloride and phosgene gas when burned. Methylene chloride-type removers should not be used in the presence of an open flame or other heat sources such as kerosene heaters (8). 

Waste Gas Streams. Several methods of decomposing phosgene in waste gas streams are used. The outlet gas from the phosgene decomposition equipment is continuously monitored for residual phosgene content to ensure complete decomposition. 

Zwart et al. (1990) exposed groups of five male and five female Wistar rats to phosgene at varying concentrations for 5, 10, 30, or 60 min. The test atmosphere was monitored at both the inlet and outlet of the glass exposure chambers by gas chromatography and infrared analysis. The 10-min LC50 value was 80 ppm, and the 30-and 60-min LC50 values were 20 and 12 ppm, respectively. 

About the size of a package of cigarettes, individual sensors are available for H2S, phosgene, N02, HCN, and CO. In the near future, the series will be expanded to include CI2 and hydrazine. When used with the Chronotox microprocessor, the Monitox serves as a personal monitor as well as a gas detection alarm system. 

In 1992, a monitoring device that detected phosgene and diphosgene in the air was patented in Germany. 

After completing decontamination, the only effective management consists of close observation for the development of respiratory distress and supportive care. There are no known antidotes for pulmonary agent exposure. Patients exposed to phosgene or diphosgene require monitoring for a minimum of 12h because of the possibility of delayed symptoms (2). Strict bed rest is essential for patients with mild and moderate exposmes, because any exertion, even minimal exertion, can shorten the clinical latent period and inaease the severity of respiratory symptoms (8). In symptomatic patients, physical activity can cause clinical deterioration and even death (8). Supportive care consists of managing secretions, bronchospasm, hypoxia, and pulmonary edema. 

Owing to the poor warning properties of the gas to the human senses, automatic continuous monitors equipped with alarm systems are recommended [36,1486,1893], and a detailed specification for such devices has been provided [1484]. Skin and eye contact with phosgene should be avoided, but contaminated clothing should be removed immediately and decontamination effected by washing. Emergency showers should be provided [1893] in any facility in which phosgene is stored, used or manufactured. 

The colour reactions of phosgene constitute the most widely published methods for its determination. They are frequently reliable, and are often amenable to continuous monitoring of effluents and the workplace environment [1255]. The earliest methods based on colour changes of reagents were developed for the rapid detection of phosgene when used as a war gas [187b,642,643,1107,2024,2243]. 

The feasibility of using infrared laser beams for the monitoring of phosgene in and around the plant has been described [ICI47-ICI49]. Phosgene has strong absorption bands at 849 (r ) and 1827 cm" (r,), but the combination band at 1011 cm" (r +rj), is less than one thirtieth of the intensity of the 1827 cm" band. The absorption data, appropriate to... 

---