Microplastics in city skies: How everyday breathing introduces tiny plastics into lungs

Researchers Warn Daily Inhalation of Urban Air Carries Dangerous Microplastic Fibres (Image: Canva)

A study by Xi’an Jiaotong University found microplastic levels in Xi’an’s air tripled after the COVID-19 pandemic, largely from disposable masks, synthetic clothing, and urban pollution. Researchers linked these fibers to PM2.5 particles, showing they can reach deep into lungs, especially in younger people, and stressed the need for better waste management, long-term monitoring, and toxicity studies to understand health impacts and reduce airborne plastic exposure in urban environments.

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Researchers at Xi’an Jiaotong University have found that microplastic levels in city air have tripled since the COVID-19 pandemic, raising concerns about airborne pollution and potential health effects for residents.

A team led by Fobang Liu analysed PM2.5 air particles across Xi’an. They compared samples collected before and after the pandemic. PM2.5 particles are fine enough to penetrate deep into lungs. The study measured seasonal changes by sampling in summer and winter. Researchers focused on aerosols from dust, smoke, and traffic emissions. Airborne microplastics were found in both rural and urban areas. The findings were published in the Journal of Geophysical Research.

Pandemic impact and sources of microplastics

Disposable masks became widely used during the COVID-19 outbreak. Many ended up as litter or in crowded bins. Laboratory studies show masks release polypropylene fibers when worn or aged. Other sources include synthetic clothing, tires, and packaging materials. Filters captured fibres such as polyethylene terephthalate, used in bottles and clothing. Sorting by colour and shape revealed material types and possible origins. Before 2020, samples showed a wide variety of plastic fibres. After the pandemic, transparent and white fibers dominated filters. Researchers linked the change to widespread use of face masks.

Environmental factors and particle dispersal

Microplastic levels were found to rise alongside ozone levels at times. Sunlight and heat cause photodegradation, breaking plastic surfaces into smaller fragments. Wind, vehicle traffic, and pedestrian movement lift particles into the air. Field studies showed microplastics travelled up to 59 miles from source. Aging and outdoor litter release fibers more easily in dry conditions. These processes illustrate how urban environments contribute to airborne pollution.

Health implications and prevention

Inhaled microplastics can enter the nose, throat, and lungs. Dosimetry models showed younger people may be more susceptible to deposition. Fibres may carry chemicals and microbes, complicating health risks. Outdoor air contributes to indoor exposure, especially in ventilated buildings. Improved waste management and cleaner streets can reduce future airborne plastics. Hospitals and cities are encouraged to track disposable gear and implement reusable mask policies. Liu’s team emphasised long-term sampling and better toxicity tests are needed. The study provides new insights into pandemic habits and city air quality.