Black carbon (BC) aerosols have severe impacts on climate and health. Most atmospheric BC loadings are now predominantly reported for the PM_2.5 size cut-off. Based on 39 published set of ambient BC concentrations from around the world where PM_2.5 and PM₁₀ were collected in parallel, we demonstrate that BC in PM_2.5 was only around 80% of that in PM₁₀. The implication is that around 20% of BC in the global ambient atmosphere is ignored with the now-legacy PM_2.5 sampling approach. Correspondingly, BC of freshly emitted particles from combustion activities is dominantly reported in terms of PM_2.5, and thus inflicting a bias in the total BC emission inventories. A consequence is that ambient BC is underpredicted when derived from models based on (PM_2.5) emission inventories. This consideration contributes to reconcile existing systematic offset between model predictions and observation-based estimates of climate-relevant effects of anthropogenic BC aerosols. We propose that total ambient BC concentration should be considered rather than the PM_2.5 portion to reduce the uncertainties in estimates of BC effects on the climate.

黑炭（BC）气雾剂对气候和健康产生严重影响。据报道，大多数大气中的BC负荷是PM _2.5尺寸的截止值。根据来自世界各地的39个已发布的环境BC浓度集合，其中并行收集PM _2.5和PM ₁₀，我们证明PM _2.5中的BC仅约为PM _10中80％的。这意味着，现在的传统PM _2.5采样方法会忽略全球环境大气中约20％的BC 。相应地，燃烧活动中新散发的颗粒的BC以PM _2.5为主。，从而导致总的BC排放清单出现偏差。结果是，从基于（PM _2.5）排放清单的模型得出的环境BC会被低估。这种考虑有助于调和模型预测与基于观测的人为BC气溶胶气候相关效应的估计之间的系统性抵销。我们建议应考虑总的环境BC浓度而不是PM _2.5部分，以减少BC对气候影响的估计的不确定性。