Institute for Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
Institute for Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
Sci Total Environ. 2014 Sep 15;493:943-53. doi: 10.1016/j.scitotenv.2014.06.072. Epub 2014 Jul 5.
Indoor and outdoor measurements of real-time ultrafine particles (UFP; N10-700 in this study) number concentration and average diameter were collected twice at 39 primary schools located in Barcelona (Spain), with classrooms naturally ventilated under warm weather conditions. Simultaneous outdoor N concentration measurements at schools under different traffic exposures showed the important role of this source, with higher levels by 40% on average at schools near heavy traffic, highlighting thus the increased exposure of children due to urban planning decisions. A well-defined spatial pattern of outdoor UFP levels was observed. Midday increases in outdoor N levels mainly attributed to nucleation processes have been recorded both at high and low temperatures in several of the outdoor school sites (increasing levels by 15%-70%). The variation of these increases also followed a characteristic spatial pattern, pointing at schools' location as a key variable in terms of UFP load owing to the important contribution of traffic emissions. Indoor N concentrations were to some extent explained by outdoor N concentrations during school hours, together with average temperatures, related with natural ventilation. Outdoor midday increases were generally mimicked by indoor N concentrations, especially under warm temperatures. At specific cases, indoor concentrations during midday were 30%-40% higher than outdoor. The time scale of these observations evidenced the possible role of: a) secondary particle formation enhanced by indoor precursors or conditions, maybe related with surface chemistry reactions mediated by O3, and/or b) UFP from cooking activities. Significant indoor N increases were detected after school hours, probably associated with cleaning activities, resulting in indoor N concentrations up to 3 times higher than those in outdoor. A wide variability of indoor/outdoor ratios of N concentrations and mean UFP sizes was detected among schools and measurement periods, which seems to be partly associated with climatic conditions and O3 levels, although further research is required.
在巴塞罗那（西班牙）的 39 所小学，教室在温暖天气条件下自然通风，我们两次采集实时超细颗粒（UFP；本研究中 N10-700）数浓度和平均直径的室内和室外测量值。在不同交通暴露情况下，对学校室外 N 浓度的同步测量表明了这一来源的重要作用，在交通繁忙的学校，平均浓度高出 40%，从而突显了城市规划决策导致儿童接触增加。观察到室外 UFP 水平具有明确的空间分布模式。在几个室外学校地点，记录到中午室外 N 水平的增加主要归因于成核过程，无论是在高温还是低温下（增加了 15%-70%）。这些增加的变化也遵循一个特征空间模式，表明学校的位置是 UFP 负荷的关键变量，因为交通排放的重要贡献。在上课时间内，室内 N 浓度在一定程度上可以由室外 N 浓度解释，同时还与自然通风相关的平均温度有关。室外中午的增加通常会被室内 N 浓度模拟，特别是在温暖的温度下。在某些情况下，中午室内浓度比室外浓度高 30%-40%。这些观察的时间尺度表明了以下两种可能的作用：a）室内前体物或条件增强的二次颗粒形成，可能与臭氧介导的表面化学反应有关，和/或 b）烹饪活动产生的 UFP。放学后检测到室内 N 浓度显著增加，可能与清洁活动有关，导致室内 N 浓度比室外高 3 倍。在学校和测量期间，检测到室内/室外 N 浓度和平均 UFP 大小的比值存在很大的变化性，这似乎部分与气候条件和臭氧水平有关，尽管还需要进一步的研究。
