People in polluted communities are often exposed to both PM and ozone (O3), albeit not always simultaneously; an important question is whether exposure to particles with seasonal compositional differences can influence biological outcomes. We addressed this question using a mouse model of cardiovascular disease by contrasting the health outcomes of exposures to particles formed or aged during periods of relatively high photochemical activity (i.e. spring/summer), which has increased ambient O3 concentrations, with outcomes of exposures to fall/winter particles which are associated with lower O3 concentrations. Electrocardiographs (ECGs) and blood pressures (BPs) were acquired following exposures to concentrated ambient particles (CAPs). ECGs were analyzed to changes in specific waveform parameters and changes in heart rate variability (HRV). Exposures elicited several types of waveform abnormalities that were associated with seasonal differences in particle constituents. Alterations in R-R interval and P-R interval were seen following exposure to summer CAPs but not fall CAPs and differential responses were seen in the corrected Q-T interval following the two seasonal exposures. Measures of HRV increased after exposure to summer CAPs compared to air-exposed controls but not following the winter CAPs exposure. There were chemical differences with respect to the organic constituents in ambient particles between summer and fall aerosol. The oxygen to carbon ratios (O:C) were generally higher in the spring and summer than in the fall, consistent with seasonal differences in atmospheric photochemical activity. Seasonal differences in atmospheric photochemical activity can modify ambient aerosol composition and can alter biological responses in the cardiovascular system. The results from this study confirm that ambient photochemical activity can alter the toxicity of ambient PM. Regional and seasonal differences in PM2.5 composition should be important considerations when evaluating the effects of PM exposure on cardiovascular health.Implications: Particles formed during periods of high photochemical activity (e.g. spring/summer) elicit more adverse cardiovascular health effects than particles formed during periods of low photochemical activity (e.g. fall/winter). Seasonal differences in atmospheric photochemical activity modified ambient aerosol composition and worsened cardiovascular responses. These results can inform regulatory agencies and may help design air quality regulations for PM2.5 that consider seasonal and regional variations.

中文翻译：

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大气PM2.5对高脂血症小鼠心血管系统的季节性影响。

受污染社区的人们经常暴露于PM和臭氧（O3）中，尽管并不总是同时发生。一个重要的问题是，暴露于具有季节性成分差异的颗粒是否会影响生物学结果。我们使用了心血管疾病的小鼠模型，通过比较暴露于相对较高的光化学活性（例如，春季/夏季）期间形成或老化的粒子（其环境O3浓度增加，而暴露的结果却下降）的健康结果，解决了这个问题与较低的O3浓度相关的冬季颗粒。在暴露于浓缩的环境颗粒（CAP）之后，获取了心电图仪（ECG）和血压（BP）。分析ECG，以改变特定波形参数和心率变异性（HRV）。暴露会引起几种类型的波形异常，这些异常与颗粒成分的季节性差异有关。暴露于夏季CAP后，RR间隔和PR间隔发生了变化，但没有下降CAP，并且在两次季节性暴露后的校正QT间隔中出现了差异响应。与暴露于空气中的对照组相比，暴露于夏季CAP后的HRV值有所增加，但与暴露于冬季CAP相比没有增加。在夏季和秋季气溶胶之间，环境颗粒中的有机成分存在化学差异。春季和夏季的氧碳比（O：C）通常比秋季高，这与大气光化学活性的季节性差异一致。大气光化学活性的季节性差异可以改变周围的气溶胶成分，并可以改变心血管系统的生物学反应。这项研究的结果证实，环境光化学活性可以改变环境PM的毒性。在评估PM暴露对心血管健康的影响时，PM2.5成分的区域和季节差异应该成为重要的考虑因素。含义：在高光化学活性（例如春季/夏季）期间形成的颗粒比在过程中形成的颗粒对心血管健康的影响更大光化学活性低的时期（例如，秋/冬）。大气光化学活性的季节性差异改变了周围气溶胶的组成，并恶化了心血管反应。