这项研究调查了2007年至2022年洛杉矶盆地环境超细颗粒(UFP)和相关空气污染物的长期趋势,重点是法规对UFP水平的间接影响。UFP的颗粒数浓度(PNC)是根据该地区以前的研究编制的,以及相关的共同污染物数据,包括氮氧化物(NOx),一氧化碳(CO),元素碳(EC),有机碳(OC),臭氧(O3)是从化学形态网络(CSN)数据库获得的。在学习期间,UFP的PNC普遍下降,NOx,EC,OC,除了CO,其浓度趋势没有表现出一致的模式。UFP,NOx,EC,与OC呈正相关,O3呈负相关,尤其是NOx。我们的分析发现了污染物趋势的两个不同的子时期:2007-2015年和2016-2022年。例如,UFP的PNC总体以-850.09颗粒/cm3/年的年增长率下降。在第一个子时期(2007-2015年),这一速度更为明显,为-1814.9颗粒/cm3/年,然后在第二个子时期(2016-2023年)放缓至-227.21颗粒/cm3/年。第一个子期(2007-2015年)显著影响了污染物水平的变化,表现出比第二个子期(2016-2022年)更明显和统计上显著的变化。自2016年以来,几乎所有主要污染物都趋于稳定,表明现行法规的影响降低,并强调需要更严格的标准。此外,该研究包括对2007年至2022年洛杉矶盆地内车辆行驶里程(VMT)趋势的分析。尽管VMT普遍增加,当前的法规和更清洁的技术似乎已经成功地缓解了PNC增长的潜在增长。总的来说,虽然观察到UFP和共污染物水平下降,这些水平的明显稳定强调了需要更严格的监管措施和先进的排放标准。
This study investigates the long-term trends of ambient ultrafine particles (UFPs) and associated airborne pollutants in the Los Angeles Basin from 2007 to 2022, focusing on the indirect effects of regulations on UFP levels. The particle number concentration (PNC) of UFPs was compiled from previous studies in the area, and associated co-pollutant data, including nitrogen oxides (NOx), carbon monoxide (CO), elemental carbon (EC), organic carbon (OC), and ozone (O3), were obtained from the chemical speciation network (CSN) database. Over the study period, a general decrease was noted in the PNC of UFPs, NOx, EC, and OC, except for CO, the concentration trends of which did not exhibit a consistent pattern. UFPs, NOx, EC, and OC were positively correlated, while O3 had a negative correlation, especially with NOx. Our analysis discerned two distinct subperiods in pollutant trends: 2007-2015 and 2016-2022. For example, there was an overall decrease in the PNC of UFPs at an annual rate of -850.09 particles/cm3/year. This rate was more pronounced during the first sub-period (2007-2015) at -1814.9 particles/cm3/year and then slowed to -227.21 particles/cm3/year in the second sub-period (2016-2023). The first sub-period (2007-2015) significantly influenced pollutant level changes, exhibiting more pronounced and statistically significant changes than the second sub-period (2016-2022). Since 2016, almost all primary pollutants have stabilized, indicating a reduced impact of current regulations, and emphasizing the need for stricter standards. In addition, the study included an analysis of Vehicle Miles Traveled (VMT) trends from 2007 to 2022 within the Los Angeles Basin. Despite the general increase in VMT, current regulations and cleaner technologies seem to have successfully mitigated the potential increase in increase in PNC. Overall, while a decline in UFPs and co-pollutant levels was observed, the apparent stabilization of these levels underscores the need for more stringent regulatory measures and advanced emission standards.