Significant changes in emission sources have occurred in the northeastern United States over the past decade, due in part to the implementation of emissions standards, the introduction and addition of abatement technologies for road transport, changes in fuel sulfur content for road and non-road transport, as well as economic impacts of a major recession and differential fuel prices. These changes in emission scenarios likely affected the concentrations of airborne submicron particles. This study investigated the characteristics of 11–500 nm particle number concentrations and their size spectra in Rochester, NY during the past 15 years (2002 to 2016). The modal structure, diurnal, weekly and monthly patterns of particle number concentrations are analyzed. Long-term trends are quantified using seasonal-trend decomposition procedures based on “Loess”, Mann-Kendall regression with Theil-Sen slope and piecewise regression. Particle concentrations underwent significant (p < 0.05) downward trends. An annual decrease of −323 particles/cm³/y (−4.6%/y) was estimated for the total particle number concentration using Theil-Sen analysis. The trends were driven mainly by the decrease in particles in the 11–50 nm range (−181 particles/cm³/y; −4.7%/y). Slope changes were investigated annually and seasonally. Piecewise regression found different slopes for different portions of the overall period with the strongest declines between 2005 and 2011/2013, followed by small upward trends between 2013 and 2016 for most size bins, possibly representing increased vehicular traffic after the recovery from the 2008 recession.

在过去十年中，美国东北部排放源发生了重大变化，部分原因是排放标准的实施，公路运输的减排技术的引入和添加，公路和非公路运输燃料硫含量的变化以及重大衰退和燃油价格差异带来的经济影响。排放情景的这些变化可能会影响空气中亚微米微粒的浓度。这项研究调查了过去15年（2002年至2016年）在纽约州罗切斯特的11–500 nm粒子数量浓度的特征及其尺寸光谱。分析了粒子数浓度的模式结构，昼夜，每周和每月模式。使用基于“黄土”的季节性趋势分解程序，具有Theil-Sen斜率的Mann-Kendall回归和分段回归来量化长期趋势。颗粒物浓度显着（p  <0.05）下降趋势。使用Theil-Sen分析估计总颗粒数浓度每年减少-323颗粒/ cm ³ / y（-4.6％/ y）。这种趋势主要是由11-50 nm范围内的颗粒减少所致（-181颗粒/ cm ³ /y；-4.7%/y）。每年和季节性调查坡度变化。分段回归发现，整个时期的不同部分的斜率不同，在2005年至2011/2013年之间下降幅度最大，其次是大多数尺寸箱在2013年至2016年之间呈小幅上升趋势，这可能表示从2008年经济衰退中恢复后的车辆交通量有所增加。