Impact of indoor building air microplastics on human living environment health: A biomechanical perspective

Introduction: Microplastics are plastic particles less than 5 mm in diameter, mainly from synthetic textiles, home decoration materials, cleaning supplies and plastic products wear. These microplastics can enter the body through respiratory inhalation, skin contact or dietary ingestion, posing a potential threat to human health. Studies have found that inhaling microplastics can trigger respiratory inflammation, allergic reactions, and even chronic respiratory diseases (such as bronchitis and asthma). Microplastic particles can accumulate in the lungs, and long-term exposure can exacerbate respiratory diseases. In addition, microplastics may also enter other organs through the blood circulation, affecting the immune system and nervous system function. In the indoor environment, the release of microplastics is closely related to daily activities, with higher concentrations of microplastics in high-frequency activity areas (such as living rooms) and greater exposure risks. Therefore, the health effects of indoor microplastic pollution on long-term residents should not be ignored, and further research on its long-term health effects and measures to reduce exposure risks are needed. Objectives: To precisely determine the concentration levels of microplastics in indoor air and comprehensively assess their potential risks to human health, with a focus on how these microplastics interact with the biomechanical aspects of the human body. Methods: This study explores the impact of indoor building air microplastics on human environmental health and analyzes the human exposure risk of microplastic distribution in different regions. Results: The results showed that the microplastic content in the living room area was 241 ± 21 n/m3, with the highest content, while the kitchen had the lowest. In the assessment of human exposure risk, subjects had the highest daily and annual exposure levels in the living room, with some experiencing symptoms such as allergies and coughing, indicating moderate exposure risk. The daily average exposure of subjects P1 and P5 could reach 1364MPS/day and 1142MPS/day, with an average annual exposure of 1,124,000 and 1,214,000 particles, respectively. Microplastics in indoor air are mainly small particles of 20–100 microns, mainly in the form of fragments, and synthetic rubber and packaging plastics are the most common types. Health risk assessment shows that individuals exposed to high concentrations of microplastics for a long time are prone to allergies, mild cough and other problems, and exposure time is negatively correlated with health scores. Daily and annual exposure levels varied significantly by region, with the living room highest and the kitchen lowest. Conclusion: The study provides quantitative data on indoor exposure levels of microplastics and provides a scientific basis for assessing their health risks. The potential harm mechanism of microplastics to respiratory tract was revealed from the perspective of biomechanics, which filled the research gap. The seriousness of microplastic pollution in indoor environment was emphasized, which provided reference for formulating indoor environmental quality standards and health protection measures. To remind the public to pay attention to the problem of indoor microplastic pollution, especially in high-frequency activity areas, such as living rooms, measures should be taken to reduce the release and accumulation of microplastics.