Styrene is highly reactive in the atmosphere, which has been identified as a hazardous air pollutant by the Clean Air Act, and as an important secondary organic aerosol (SOA) precursor. In this study, the SOA formation from styrene under different NO_x and relative humidity (RH) conditions were explored in an indoor chamber. The chemical composition of SOA was characterized using a Fourier transform infrared spectroscopy (FTIR) and a modified atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The results show that the SOA yields decrease from 11.4% to 7.2% at about 70 μg m⁻³ SOA as RH increases from 8.5% to 62.4% in the H₂O₂ system; the SOA yields decrease from 1.1% to 0.7% at about 10 μg m⁻³ SOA as RH increases from 8.4% to 60.9% in the NO_x system. In the H₂O₂ system, C₇ and C₈ series compounds are major components of SOA at both RHs. The total signal ratio of less oxidized C₇ and C₈ compounds (n_O < 4) to the total SOA at 8.8% RH is 2.2 times higher than that at 63.3% RH. The OSc values of SOA were determined to be −0.2 at 8.8% RH and 0.04 at 63.3% RH based on MS data. It is proposed that high RH can accelerate the heterogeneous uptake of H₂O₂ onto particles and promote the further oxidation of less oxidized compounds in the particle phase. In the NO_x system, SOA formation is significantly suppressed by the competitive reaction of RO₂ with NO. The FTIR and MS results show that the main composition of SOA is organonitrates. At 8.3% RH, OH, O₃ and NO₃ are oxidants in the styrene-NO_x irritation system. Among these oxidants, NO₃ plays a minor role due to its photolysis. While at 60.9% RH, SOA formation from O₃ is significantly inhibited by the reaction of stabilized Criegee intermediates (SCIs) with H₂O, and SOA from the NO₃ pathway is suppressed by the heterogeneous uptake of N₂O₅ to humid particles.

苯乙烯在大气中具有高度反应性，已被《清洁空气法》确定为有害空气污染物，并且是重要的二次有机气溶胶 (SOA) 前体。在这项研究中，在室内室中探索了在不同 NO _x和相对湿度 (RH) 条件下由苯乙烯形成的 SOA 。SOA 的化学成分使用傅里叶变换红外光谱 (FTIR) 和改进的大气压化学电离质谱 (APCI-MS) 进行表征。结果表明，在H ₂ O ₂系统中，随着RH从8.5%增加到62.4%，SOA产率在约70 μg m ^-3 SOA下从11.4%减少到7.2% ；SOA 产量在约 10 μg m ^{-3 时}从 1.1% 降至 0.7%SOA 随着 RH 在 NO _x系统中从 8.4% 增加到 60.9% 。在H ₂ O ₂系统中，C ₇和C ₈系列化合物是两个RH 处SOA 的主要成分。 在 8.8% RH 下，较少氧化的 C ₇和 C ₈化合物（n _O < 4）与总 SOA的总信号比是 63.3% RH 下的 2.2 倍。基于 MS 数据，SOA 的 OSc 值在 8.8% RH 下确定为 -0.2，在 63.3% RH 下为 0.04。有人提出，高 RH 可以加速 H ₂ O ₂向颗粒上的异质吸收，并促进颗粒相中较少氧化的化合物的进一步氧化。在NO _XRO ₂与NO的竞争反应显着抑制了SOA 的形成。FTIR和MS结果表明SOA的主要成分是有机硝酸盐。在 8.3% RH 下，OH、O ₃和 NO ₃是苯乙烯-NO _x刺激系统中的氧化剂。在这些氧化剂中，NO ₃由于其光解作用而起次要作用。而在 60.9% RH 时，稳定的 Criegee 中间体 (SCIs) 与 H ₂ O的反应显着抑制了O _{3 的}SOA 形成，并且来自 NO ₃途径的SOA被 N ₂ O ₅对潮湿颗粒的异质吸收抑制.