Abstract:
Microplastics are ubiquitously pervasive throughout the environment, but unlike aquatic and
terrestrial microplastics, airborne microplastics have received less scientific attention. This
study is the first of its kind to explicitly examine microplastics in the indoor and outdoor air
(PM2.5) samples collected using active air samplers in Islamabad, Pakistan. The suspected
synthetic particles were analyzed using ATR-FTIR, μ-Raman and SEM-EDX to categorize
them based on their morphological characteristics, polymeric composition, and elemental
makeup. Microplastics were found in all indoor and outdoor air samples, with indoor air
samples (4.34 ± 1.93 items/m3
) being significantly more contaminated than outdoor air
samples (0.93 ± 0.32 items/m3
) (P<0.001). Among all the indoor air samples, samples taken
from classroom (6.12 ± 0.51 items/m3
) were more contaminated than samples taken from
hallway (4.94 ± 0.78 items/m3
) and laboratory (1.96 ± 0.44 items/m3
). Fibers were found to
be the prevalent shape type in indoor and outdoor airborne microplastics followed by
fragments. Transparent- and black colored microplastic particles were predominant in both
indoor and outdoor air samples. According to ATR-FTIR analysis, polyethylene terephthalate
(PET), polyethylene (PE), polypropylene (PP), and polystyrene (PS) were the most prevalent
polymer types in both indoor and outdoor environments. Results from μ-Raman analysis
corroborated the presence of the polymers identified by ATR-FTIR. Morphological analysis
of particles by SEM indicated signs of weathering on particles’ surface i.e., grooves, breaks,
shredded edges, pits etc. SEM-EDX of randomly chosen particles unraveled the presence of
C and O as core elements, along with the presence of heavy metals at some spots due to
foreign material adhering to their surface. Correlation analysis of environmental factors i.e.,
PM2.5, relative humidity, temperature, and wind speed with MPs abundance revealed non-
significant relationships. The findings of this study call for further research on airborne MPs
to better comprehend their dispersion, toxicity, interactions with other air pollutants, and
attributable health risks.
