Quantification of Airborne Microplastics in Public Libraries by Pyr‐GC‐Orbitrap‐MS and Human Exposure Assessment

Microplastics (MPs) are anthropogenic emerging contaminants which have been detected in the air, raising global concerns about their effects on the environment as well as human health. This study presents the first investigation of MP concentration in indoor air, specifically in public libraries located in Barcelona (Spain), an environment that has remained largely unexplored in this context. To achieve this, we employed the pyrolysis gas chromatography coupled to high‐resolution mass spectrometry (Pyr‐GC/MS) method targeting nine of the most widely used plastic polymers: polyethylene, polycarbonate, polymethyl methacrylate, polypropylene, nitrile butadiene rubber, polyvinyl chloride, polyethylene terephthalate, acrylonitrile butadiene styrene and polystyrene. The method enables the quantification of the ions in air samples by means of external calibration with high accuracy and precision. Morphological analysis revealed fibres as the predominant particle shape, and polymer identification showed that polyethylene was the only polymer detected in 100% of the samples with a concentration of up to 5.1 μ g m −3 of air, indicating sources such as textiles, containers and appliances brought inside the libraries by visitors. While the other polymers′ concentration was below the method detection limit, their presence cannot be excluded. The results have been used to assess the inhalation of MP in libraries based on typical adult respiratory volumes, revealing that during a 3‐h stay in a library, an adult might inhale up to 7.1 μ g of MP, while a child might inhale 2.0 μ g of MP. Currently, no evidence‐based threshold has been established to determine the concentration of MP that poses a risk to human health, precluding definitive conclusions on the health risks of estimated inhalation exposure.