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Microplastic occurrence in settled indoor dust in schools
Mohammad Javad Nematollahi1, Fatemeh Zarei1, Behnam Keshavarzi1
1Department of Earth Sciences, College of Sciences, Shiraz University, 71454 Shiraz, Iran.
Abstract:
This study examines for the first time the characteristics and human exposure of microplastics (MPs) in settled indoor dust in schools. An average of 195 MPs·g-1 of dust were detected in settled indoor composite dust samples from 28 schools in Shiraz. White-transparent microfibres with lengths 500-1000 microm were the most abundant type of MP found among the samples examined. Polyethylene terephthalate and polypropylene MPs were dominant across all types of MP found including microfibres. MPs had generally smooth morphology with sharp or regular edges which could have been released to the environment as primary MPs. Among all sampling sites, higher concentrations of MPs were found in the south and centre of the city. These were areas affected by high population density, high traffic load and high presence of industrial units and workshops. Principal Component Analysis (PCA) showed a positive strong correlation between sampling sites and MP physical characteristics. The PCA plots revealed that MP sheets and fragments were prevalent in sites in the North of Shiraz, whereas microfibres were mainly associated with sites in the South. The levels of MPs in the South of Shiraz were greater than in the rest of the country and the wind direction and topography were found to be important factors affecting the MP distribution observed. Compared to other population groups, elementary school students had relatively high exposure risk to MPs. This study reveals that microfibres are widespread in Shiraz' schools and pose a high exposure risk to MPs for young students.
Insights
Microplastics (MPs) are prevalent in Shiraz schools, averaging 195 MPs per gram of dust. Young students face high exposure risks, particularly from microfibers found in settled indoor dust.
Area of Science:
- Environmental Science
- Toxicology
- Public Health
Background:
- Microplastics (MPs) are a growing environmental concern, with indoor dust identified as a potential exposure pathway.
- Limited research exists on MP characteristics and human exposure within indoor environments like schools.
Purpose of the Study:
- To investigate the characteristics and human exposure of microplastics in settled indoor dust in schools.
- To determine the types, abundance, and distribution of MPs in school dust samples.
- To assess the potential exposure risks for elementary school students.
Main Methods:
- Collected settled indoor composite dust samples from 28 schools in Shiraz.
- Analyzed dust samples for microplastic identification, quantification, and characterization (type, size, morphology).
- Utilized Principal Component Analysis (PCA) to correlate MP characteristics with sampling site factors.
Main Results:
- An average of 195 MPs per gram of dust was detected.
- White-transparent microfibers were the most abundant MP type, with polyethylene terephthalate and polypropylene being dominant.
- Higher MP concentrations were found in the south and center of Shiraz, correlating with population density, traffic, and industrial activity.
- Microfibers were predominantly associated with southern sites, while MP sheets and fragments were found in northern sites.
Conclusions:
- Microfibers are widespread in Shiraz schools, posing a significant exposure risk to young students.
- Factors such as wind direction and topography influence MP distribution.
- Indoor settled dust in schools represents a critical reservoir for microplastic exposure, particularly for vulnerable populations.
