Phosgene threshold limit value

However, phosgene is clearly highly toxic (threshold limit value-TLV of 0.1 ppm), but acrolein, for example, has the same TLV and is produced in quantities of several millions worldwide. Acrolein is also produced at barbecue parties by roasting foods, without provoking health alarms. Clearly, a low TLV implies the adoption of special safety procedures and limited storage. On-demand production and other safety procedures, such as those discussed above, are the solution to minimizing the risk to a sustainable level. 

A regulation indicating the maximum permissible airborne concentration of a dangerous compound in a place of work over 8 hours a day is enforced on the basis of threshold limiting values (TLVs). These are collected in lists and a selection of TLVs of phosgenation reagents is given in Table 3.4 in Chapter 3. 

Infrared spectroscopic methods are particularly suitable for the determination of phosgene at concentrations below the currently established threshold limit value. Measurements of low concentrations (25-500 ppb) [14] have been reported. Phosgene has strong absorption bands at 849 and 1827 cm , but the intensity of the combination band at 1011 cm is less than one-thirtieth of that at 1827 cm . ... 

A time-weighted average threshold limit value (TLV-TWA) for phosgene of 0.1 ppm (0.4 mg/m ) for an 8-hour workday has been adopted by the U.S. Occupational Safety and Health Administration (OSHA) and the American Conference of Governmental Industrial Hygienists. [1] and [2]... 

Phosgene is manufactured from a reaction of carbon monoxide and chlorine gas in the presence of activated charcoal. Phosgene is used in the manufacture of isocyanates, polycarbonates, pesticides, dyes, and pharmaceuticals. Manufacture of phosgene in the United States is almost entirely captive in that more than 99% is used in the manufacture of other chemicals within a plant boundary (US EPA, 2003). The odor threshold is between 0.5 and 1.5 ppm (NIOSH, 1976) unfortunately, the odor threshold is inadequate to protect against toxic inhalant exposure because damage to the deep respiratory tract can take place at lower concentrations (Sidell et al., 1997). Phosgene has an odor safety classification rating of "E," which indicates that fewer than 10% of attentive persons can detect the Threshold Limit Value (TLV) (Amoore and Hautala, 1983). 

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