Air quality in schools and children'S exposure to particulate pollution in barcelona
- Autores: Ioar Rivas Lara
- Directores de la Tesis: Xavier Querol Carceller (dir. tes.), Jordi Sunyer i Deu (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2015
- Idioma: inglés
- Tribunal Calificador de la Tesis: Giorgio Buonanno (presid.), David Gabriel Buguña (secret.), Susana Marta Almeida (voc.)
- Materias:
- Enlaces
- Resumen
Exposure to air pollutants has been widely linked to negative health effects. Children are particularly vulnerable since they have higher ventilation rates and levels of physical activity and, therefore, they receive higher doses of air pollutants than adults.
In the framework of BREATHE Project, a sampling campaign in the indoor and outdoor environments of 39 schools in Barcelona and Sant Cugat del Vallès was carried out to characterise air quality in schools. The same pollutants were also monitored in an urban background station in Barcelona (UB-PR).
The results evidence that concentrations of equivalent black carbon (EBC), NO2 and ultrafine particles (UFP) in schools showed an increasing gradient towards the city centre, following the traffic density in the city. However, the impact of local school sources prevent the particulate matter with an aerodynamic diameter<2.5 µm (PM2.5) from being a good indicator of traffic emissions in schools.
Concentrations in the playgrounds were 1.6 times higher than indoors for NO2 and 1.5 times higher for UFP, while EBC concentrations were similar in both environments. On the contrary, PM2.5 had 1.6 times higher concentration indoors because organic carbon (OC; the most important contributor to indoor PM2.5), Ca, and Sr were mainly generated indoors.
A source apportionment analysis by Positive Matrix Factorization (PMF) allowed the identification of eight factors or sources (mineral, traffic, road dust, secondary sulphate and organics, secondary nitrate, sea spray, heavy oil combustion, metallurgy) which corresponded to well-known sources of PM in the study area, plus a ninth factor which was observed for the first time. This factor was named organic/textile/chalk and characterised by OC (from cotton fibres, skin flakes, etc.), Ca and Sr (from blackboard chalk). The mineral factor was especially dependant on the type of playground (sandy or paved). Much lower mineral contributions were found in UB-PR than in schools, also indicating that this is a mainly local source. Mineral and organic/textile/chalk sources were responsible for the very high concentrations in the indoor environment (37 µg·m-3) and for almost doubling concentrations in playgrounds (29 µg·m-3) than in UB-PR (17 µg·m-3).
Contributions from traffic emissions were quite similar at the three studied environments: classrooms (4.8 µg·m-3), playgrounds (5.5 µg·m-3) and UB-PR (4.1 µg·m-3). EBC showed one of the highest Finf, with the 92% of indoor EBC coming from the outside during the warm season and 75% during the cold one. These results point out the necessity to locate future schools far away from trafficked streets.
NO2 showed a similar infiltration degree in the warm and cold seasons, thus independently of the windows opening or closing. Indoor-to-outdoor correlations showed low R2 and infiltration factors (Finf) for UFP because of indoor particle sources (the intercepts were high). However, indoor levels of UFP were still influenced by those outdoors.
Simultaneously to school measurements, EBC personal measurements of 45 children were carried out. The EBC concentrations were higher in personal measurements than in schools owing to peak concentration events that took place mainly during commuting time. Children spent 6% of their time on commuting but received 20% of their daily EBC dose, due to co-occurrence with road traffic rush hours and the proximity to the source. Exposure could be significantly different, even between children attending the same school, and this variability could not be taken into account only with the fixed stations. Children received 37% of their daily-integrated EBC dose at school. Indoor environments (classroom and home) were responsible for the 56% EBC dose.
This thesis provides an in-depth analysis of air quality in schools and children¿s exposure and dose. The results obtained are thought to be valuable for policy makers and urban planners.
