Sampling airborne microplastics and fibers: lessons learned from Aveiro, Portugal

, C. Prata Joana, L. Castro Joana, P. Da Costa João, Duarte Carlos, Cerqueira Mário, Rocha-Santos Teresa.

Airborne microplastics and fibers can easily be inhaled, which causes increasing concerns over their environmental concentrations and toxic effects. However, the difficulty of sampling air can be felt in the need for specific equipment (e.g. air samplers) as well as the presence of other particulate matter and potential contaminations from the laboratory air. The objective of this work is to identify potential solutions for routine quantification, based on works conducted in Aveiro, Portugal. A first challenge was separating natural from synthetic fibers. A myriad of laboratory tests showed this could not be easily achieved through density separation, chemical digestion, or the use of staining dyes. The identification of fibers as natural or synthetic can only rely on visual characteristics for routine quantification. Based on the observation of multiple textile fibers, a diagram of identification has been produced based on the more regular structure of synthetic fibers. However, the identification of fibers and microplastics was hindered by the presence of other particulate matter. A method based on the removal of organic matter by H2O2 and density separation by NaI was developed and tested, with recovery rates of 94%. The use of both developed techniques in real sampling efforts allowed further improvements in contamination control measures, identifying possible sources as unfiltered work solutions, air deposition of fibers released from paper towels and cotton lab coats, directly weighting filters, and accumulation of dust in the sample inlet requiring proper decontamination procedures. Together, these developments allow a simple, fast, and reliable procedure which can be applied to determine concentrations of airborne microplastics and fibers.

View online