Cold start emissions at+22, -7 and -20°C ambient temperatures from a three-way catalyst (TWC) car:: regulated and unregulated exhaust components

A project initiated by the Swedish Environmental Protection Agency (SEPA) concerning cold start driving conditions is partially reported in the present paper. A three-way catalyst car was run in accordance with the European driving cycle (EDC) at 22 degrees C, -7 degrees C and -20 degrees C ambient temperatures. The diluted exhaust was analyzed for: Carbon monoxide (CO), unburned fuel hydrocarbons (HC), oxides of nitrogen (NOx), particulates, light aromatics, alkenes, green house gases, aldehydes and polycycIic aromatic hydrocarbons (PAH) in particles and in the gaseous phase. As expected, the emission factors of both regulated and unregulated exhaust components increased at lower ambient temperatures. However, the emissions did not increase uniformly. The mutagenic/carcinogenic compound benz[a]pyrene for example, increased more than 100 times while CO and HC only increased 5-20 times at the lowest ambient temperature studied. (C) 1999 Elsevier Science B.V. All rights reserved.