2020 Yes https://www.mdpi.com/1660-4601/17/10/3685 van Drooge, Barend Europe Observational Elementary (K-5) Primary schools Polycyclic aromatic hydrocarbons (PAHS) Trap Indoor air quality Playgrounds Organic aerosol Traffic emissions were the main
contributors of PAHs to the atmospheres in all schools, with higher average concentrations in those
located downtown (1800–2700 pg/m3) than in the periphery (760–1000 pg/m3). The similarity of
the indoor and outdoor concentrations of the PAH is consistent with a transfer of outdoor traffic
emissions to the indoor classrooms. This observation was supported by the hopane and elemental
carbon concentrations in PM2.5, markers of motorized vehicles, that were correlated with PAHs.
The concentrations of food-related markers, such as glucoses, sucrose, malic, azelaic and fatty acids,
were correlated and were higher in the indoor atmospheres. These compounds were also correlated
with plastic additives, such as phthalic acid and diisobutyl, dibutyl and dicyclohexyl phthalates.
Clothing constituents, e.g., adipic acid, and fragrances, galaxolide and methyl dihydrojasmonate
were also correlated with these indoor air compounds. All these organic tracers were correlated with
the organic carbon of PM2.5, which was present in higher concentrations in the indoor than in the
outdoor atmospheres.