Previous source apportionment analyses of New York City (NYC) PM_2.5 have found that transported pollution can account for up to half of total fine particulate matter (PM_2.5) mass. In recent years, several local and federal emissions regulations on both the transportation and energy sector have been introduced, such as the Clean Heavy-Duty Bus and Truck Rule, and policies related to the NYC Clean Heat Program. Since the implementation of these regulations, there have been limited studies on regional transport of particulate air pollution into NYC. This paper aims to quantify long-term changes in local and regional contributions to PM_2.5 in NYC. The composition of PM_2.5 in NYC over the period 2002–2018 was evaluated using data from the US Environmental Protection Agency (EPA) Chemical Speciation Network (CSN) and the New York City Community Air Survey (NYCCAS). Background site data obtained from EPA CSN was used to assess regional transport. Two estimates of transported PM_2.5 were calculated, one assuming that transported PM_2.5 consists solely of ammonium sulfate and ammonium nitrate as a lower bound and the other taking into account organic matter (OM) as an upper bound. Using this method, regional transport was estimated to account for 25–46% of total PM_2.5 measured in NYC in 2018, down from 46 to 57% in 2002. Secondary PM_2.5 output from the Community MultiScale Air Quality (CMAQ) model for the years 2008, 2011, and 2017 was used as an additional upper-bound estimate of regional transport (56%, 35%, and 30%, respectively). In addition to CMAQ model estimates of sulfate, nitrate, and primary emitted PM_2.5, land-use regression (LUR) models for sulfur, vanadium, copper, nickel, and PM_2.5 measurements at 60 locations across NYC during the winter and summer seasons of 2008–2015 were assessed for changes in local emissions. The results indicate decreased emissions from residual oil burning, traffic, and ships. As a consequence of regional and local changes, PM_2.5 in NYC had fallen to approximately 55% of its 2002 levels by 2018. The observed temporal and spatial trends of PM_2.5 and its components point to the effect of regulations as well as economic influences on fuel usage, such as the decline of coal in favor of natural gas, in reducing air pollution over the last two decades. While other major PM_2.5 constituents have declined, OM is becoming an increasingly dominant component with potential implications for PM_2.5 toxicity. Further improvements in NYC air quality could be achieved by targeting sources of ambient OM, such as commercial cooking, traffic, and biomass burning for residential heating.

纽约市（NYC）PM _2.5以前的来源分配分析发现，运输的污染最多可占总细颗粒物（PM _2.5）质量的一半。近年来，针对交通和能源领域的一些地方和联邦排放法规已经出台，例如《清洁重型公共汽车和卡车规则》以及与纽约市清洁热计划有关的政策。自从这些法规实施以来，对将微粒空气污染转移到纽约市的研究很少。本文旨在量化纽约市PM _2.5局部和区域贡献的长期变化。PM _2.5的组成使用美国环境保护署（EPA）化学物种形成网络（CSN）和纽约市社区空气调查（NYCCAS）的数据对2002-2018年间纽约市的空气质量进行了评估。从EPA CSN获得的背景站点数据用于评估区域运输。计算了运输的PM _2.5的两个估计值，一个假设运输的PM _2.5仅由硫酸铵和硝酸铵组成，作为下限，另一个假设有机物（OM）作为上限。使用这种方法，估计区域交通占纽约市2018年PM _2.5总量的25–46％，从2002年的46％降至57％。中学PM _2.5社区多尺度空气质量（CMAQ）模型在2008年，2011年和2017年的输出被用作区域交通的额外上限估计值（分别为56％，35％和30％）。除了CMAQ模型估算的硫酸盐，硝酸盐和主要排放的PM _2.5之外，在纽约州的冬季和夏季期间，纽约市60个地点的硫，钒，铜，镍和PM _2.5的土地利用回归（LUR）模型也进行了测量。对2008-2015年当地排放量的变化进行了评估。结果表明，残留燃油燃烧，交通和船舶产生的排放减少了。由于区域和地方的变化，到2018年，纽约市的PM _2.5降至其2002年水平的约55％。观察到的PM的时空趋势_2.5及其组成部分指出了法规的影响以及对燃料使用的经济影响，例如在过去的二十年中减少了对空气污染的煤炭的减少，取而代之的是天然气。虽然其他主要的PM _2.5成分有所下降，但OM逐渐成为占主导地位的组件，对PM _2.5毒性具有潜在的影响。通过瞄准周围OM的来源，例如商业烹饪，交通运输和用于住宅取暖的生物质燃烧，可以进一步改善NYC空气质量。