Low-cost particulate matter (PM) sensors are increasingly used by researchers, public health agencies, and the public to measure spatial and temporal variations in air pollution, which can inform strategies for community air pollution reduction. While low-cost PM sensors provide a valuable measure of harmful fine particulate matter (PM), a significant portion of ambient PM is typically the secondary product of air pollution emitted by varied sources outside of community boundaries. In contrast, concentrations of black carbon (BC), a component of PM, are directly emitted by a few specific sources, such as diesel engines within communities. Motivated by community organizations seeking to understand persistent sources of local pollution, this study deployed a suite of custom-built BC sensors alongside a network of low-cost PM sensors for four weeks in two seasons at 50 stationary locations in the adjacent cities of Richmond, North Richmond, and San Pablo, California, east of the San Francisco Bay. Concentrations of BC varied more than PM both temporally and spatially. Monthly network-average BC was 3 × higher in winter than late spring, while PM was only 10% lower. In both seasons, average PM concentrations at two-thirds of sites were ±10% of the network average, whereas two-thirds of sites had BC levels ±10% of the network-average concentration. The most and least polluted locations were more persistent across seasons for BC than PM, and the temporal dynamics of BC at these sites were similar, signifying that they are impacted by the same emission sources. Together, these spatiotemporal trends show that BC is a better indicator of the proximity and activity of local pollution sources than PM. Thus, including BC in addition to PM in community monitoring networks can provide additional insights about local sources of air pollution.

中文翻译：

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添加黑碳对颗粒物社区监测的价值

研究人员、公共卫生机构和公众越来越多地使用低成本颗粒物 (PM) 传感器来测量空气污染的空间和时间变化，这可以为减少社区空气污染的策略提供信息。虽然低成本 PM 传感器可以对有害细颗粒物 (PM) 进行有价值的测量，但环境 PM 的很大一部分通常是社区边界之外各种来源排放的空气污染的二次产品。相比之下，PM 成分之一的黑碳 (BC) 浓度是由一些特定来源直接排放的，例如社区内的柴油发动机。在寻求了解当地持久污染源的社区组织的推动下，这项研究在里士满邻近城市的 50 个固定地点在两个季节中部署了一套定制的 BC 传感器以及低成本 PM 传感器网络，为期四个星期，北里士满和加利福尼亚州圣巴勃罗，旧金山湾以东。 BC 浓度在时间和空间上的变化均大于 PM。冬季的月网络平均 BC 比春末高 3 倍，而 PM 仅低 10%。在这两个季节，三分之二的站点的平均 PM 浓度为网络平均浓度的 ±10%，而三分之二的站点的 BC 水平为网络平均浓度的 ±10%。 BC 污染最严重和污染最少的地点比 PM 更持久，并且这些地点的 BC 时间动态相似，这表明它们受到相同排放源的影响。总之，这些时空趋势表明，BC 比 PM 更能指示当地污染源的邻近性和活动性。因此，除了 PM 之外，将 BC 纳入社区监测网络可以提供有关当地空气污染源的更多见解。