Department of Civil and Environmental Engineering, University of California, Berkeley , Berkeley, California 94720-1710, United States.
Environ Sci Technol. 2013 Sep 3;47(17):10022-31. doi: 10.1021/es401034z. Epub 2013 Aug 19.
A fuel-based approach is used to estimate long-term trends (1990-2010) in carbon monoxide (CO) emissions from motor vehicles. Non-methane hydrocarbons (NMHC) are estimated using ambient NMHC/CO ratios after controlling for nonvehicular sources. Despite increases in fuel use of ∼10-40%, CO running exhaust emissions from on-road vehicles decreased by ∼80-90% in Los Angeles, Houston, and New York City, between 1990 and 2010. The ratio of NMHC/CO was found to be 0.24 ± 0.04 mol C/mol CO over time in Los Angeles, indicating that both pollutants decreased at a similar rate and were improved by similar emission controls, whereas on-road data from other cities suggest rates of reduction in NMHC versus CO emissions may differ somewhat. Emission ratios of CO/NOx (nitrogen oxides = NO + NO2) and NMHC/NOx decreased by a factor of ∼4 between 1990 and 2007 due to changes in the relative emission rates of passenger cars versus diesel trucks, and slight uptick thereafter, consistent across all urban areas considered here. These pollutant ratios are expected to increase in future years due to (1) slowing rates of decrease in CO and NMHC emissions from gasoline vehicles and (2) significant advances in control of diesel NOx emissions.
采用基于燃料的方法来估计机动车一氧化碳（CO）排放的长期趋势（1990-2010 年）。非甲烷碳氢化合物（NMHC）是在控制非车辆源后，根据环境 NMHC/CO 比值估算得出的。尽管燃料使用量增加了约 10-40%，但在 1990 年至 2010 年间，洛杉矶、休斯顿和纽约市的道路车辆运行尾气中的 CO 排放量减少了约 80-90%。在洛杉矶，NMHC/CO 的比值随时间变化稳定在 0.24±0.04mol C/mol CO，表明两种污染物以相似的速率下降，并且受到相似的排放控制措施的改善，而其他城市的道路数据表明，NMHC 与 CO 排放量的减少率可能略有不同。由于乘用车与柴油卡车的相对排放率发生变化，以及此后略有上升，CO/NOx（氮氧化物=NO+NO2）和 NMHC/NOx 的排放比值在 1990 年至 2007 年间下降了约 4 倍，这在所有考虑的城市地区都是一致的。由于（1）汽油车 CO 和 NMHC 排放量下降速度放缓，以及（2）柴油 NOx 排放控制取得重大进展，这些污染物比值预计将在未来几年内增加。
