From chemical smokes and explosives

However, the initiation temperature of the ensuing reaction, equation (3.7), between phosgene and zinc oxide (which also results in the formation of oxide chloride, see Section 9.5.7) is sufficiently low (ca. 220 C) compared to the temperature of the burning composition that the concentration of phosgene in the smoke cloud is low [1033]. 

Deflagration of l,3,5-trichloro-2,4,6-trinitrobenzene on heating to 340-350 C at constant pressure (1 atm) gave a gas mixture consisting of only 0.3% COCl. Detonation at constant volume in a bomb, however, under a pressure of 10-50 atm of inert gas, gave an explosive mixture containing 12-15% COClj upon cooling [1371,1814]. 

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