Assessing air pollution exposure in children at school: toward a source-specific exposure matrix

Children's exposure to airborne pollutants at school is a growing health concern, rarely investigated in detail. Our work aimed to implement a tool to quantify such exposure in the absence of measures.A literature review was conducted to identify potential indoor and outdoor contaminants sources in school environments, informing the development and validation of a School Exposure Matrix (SEM) for the structured assessment of schoolchildren's exposure.SEM allows the identification of 252 airborne pollutants (131 from indoors and 121 from outdoors due to outdoors/indoors transfer in schools) from 35 sources. SEM incorporates established pollutants like nitrogen dioxide, carbon monoxide, volatile organic compounds (VOCs), and particulate matter of different sizes as well as emerging airborne pollutants such semi-volatile VOCs, microbial VOCs, and biocontaminants, which arise from various sources, including traffic, combustion, school-related activities, cleaning products, furniture, office supplies, the building's structural elements, and human contacts. Additionally, SEM allows to quantify multipollution in a school as the total sum of pollutants present in the school across all the sources, according to various multipollution levels.SEM serves as a tool for assessing exposure in the school environment, offering insights into the pollutants that children encounter during their school activities..