title: Outdoor and indoor UFP in primary schools across Barcelona.
abstract: 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.
authors.affiliation: Institute for Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain. Electronic address: cristina.reche@idaea.csic.es.
authors.forename: C
authors.initials: C
authors.lastname: Reche
authors.affiliation: Institute for Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Viana
authors.affiliation: Institute for Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain; Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Spain; Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona (UAB), Bellaterra, Cerdanyola, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Rivas
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Spain.
authors.forename: L
authors.initials: L
authors.lastname: Bouso
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Spain.
authors.forename: M
authors.initials: M
authors.lastname: Àlvarez-Pedrerol
authors.affiliation: Institute for Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Alastuey
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Hospital del Mar Research Institute (IMIM), Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP), Spain.
authors.forename: J
authors.initials: J
authors.lastname: Sunyer
authors.affiliation: Institute for Environmental Assessment and Water Research (IDÆA-CSIC), Barcelona, Spain.
authors.forename: X
authors.initials: X
authors.lastname: Querol
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring; D052638:Particulate Matter / Q000032:analysis*; D012574:Schools; D013030:Spain; D014691:Ventilation
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: Children's exposure; Cleaning; Ozone; Photochemistry; Traffic-related UFP