Not the ocean: Study uncovers true origin of airborne microplastics

Microplastics circulating in the atmosphere are being driven largely by land-based sources, overturning long-held assumptions about the ocean’s role in global plastic spread. New research indicates that land emits more than 20 times as many microplastic particles into the air as marine environments.

The findings, published in Nature, suggest earlier estimates of atmospheric plastic pollution were significantly inflated. Scientists say the atmosphere acts as a key transport system, carrying microscopic plastic fragments across continents and into remote regions.

These particles, generated from sources such as tyre wear, synthetic fibres and contaminated surfaces, can be inhaled by humans and animals. Once airborne, they eventually settle, contributing to pollution in soils and oceans far from their original source.

The study was conducted by researchers at the University of Vienna, who combined global observational data with atmospheric modelling. A total of 2,782 measurements of airborne microplastics were analysed and compared against existing emission models.

Results showed that earlier models consistently overestimated both the concentration of microplastics in the air and their rate of deposition on Earth’s surface, in some cases by several orders of magnitude. This discrepancy enabled researchers to recalibrate emission estimates more accurately for both land and ocean sources.

Even after adjustments, land remained the dominant contributor to airborne microplastics. However, the study noted that ocean-derived particles tend to be larger, meaning their overall mass in the atmosphere may still exceed that of land-based particles despite their lower numbers.

Researchers emphasised that significant gaps in data remain. The relative contribution of sources such as traffic versus other activities is still unclear, and uncertainties around particle size distribution continue to affect estimates of total atmospheric plastic.

The study highlights the need for more comprehensive measurements to better understand how microplastics move through the atmosphere and their potential impact on environmental and human health.