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Airborne micro- and nanoplastics revealed at the submicron scale using an optimized Nile Red–confocal microscopy workflow: Implications for inhalation exposure
Original title: Airborne micro- and nanoplastics revealed at the submicron scale using an optimized Nile Red–confocal microscopy workflow: Implications for inhalation exposure
Summary
Scientists developed a better microscope technique to spot the tiniest plastic particles floating in the air—ones smaller than a grain of pollen—that older methods were likely missing. Using this method on air samples from Vietnam, they found the air was packed with these super-small plastic bits, which matter because the smallest particles are the ones most likely to reach deep into our lungs when we breathe. This suggests we may have been underestimating how much airborne plastic pollution people actually inhale, highlighting the need for better air quality monitoring tools going forward.
Airborne micro- and nanoplastics (MnPs) are emerging atmospheric contaminants of increasing concern for inhalation exposure. However, their environmental quantification remains highly uncertain due to limited detection capability in the submicron range and insufficient validation of fluorescence selectivity. Here, we developed and validated an optimized Nile Red-assisted confocal laser scanning microscopy (NR-CLSM) workflow enabling direct on-filter detection of airborne MnPs down to 0.3 μm. An optimized excitation-emission configuration (561/570-670 nm) significantly enhances particle recovery while maintaining high polymer selectivity. Common nonpolymeric particulates, including mineral particles, activated carbon, and plant-derived debris, exhibit negligible fluorescence interference under the optimized conditions. Application to total suspended particulate samples collected in suburban Vietnam revealed MnPs concentrations ranging from 1.2 × 10⁴ to 2.5 × 10⁴ particles Nm⁻³ , with submicron and fine particles (0.3-2.5 μm) constituting the dominant fraction. Comparative imaging further demonstrated that non-optimized fluorescence configuration can substantially underestimate airborne MnPs abundance, particularly in the submicron size range. Optical validation using point spread function and full width at half maximum analysis confirmed that the observed submicron fluorescence signals correspond to discrete plastic particles rather than background artifacts. By reducing analytical bias and improving detection reliability, this validated NR-CLSM workflow provides a robust foundation for standardized monitoring and more accurate assessment of inhalation exposure to airborne plastic contaminants.