A new real-time monitoring system captures minute-by-minute changes in toxic metals resulting from traffic pollution. Research indicates that non-exhaust sources, including brake wear, significantly contribute to urban health risks.
Every breath you take in a busy urban environment contains fine and ultrafine particles a thousand times smaller than a human hair, with toxic metals embedded within them. New research from National Taiwan University reveals how advanced monitoring technology is transforming our understanding of their health impacts.
The breakthrough study, published in the Journal of Hazardous Materials, demonstrates how a novel real-time monitoring system with high temporal resolution enhances the precision and accuracy of assessing cancer risks from traffic-generated heavy metals.
The collaborative research team, led by Professor Ta-Chih Hsiao from the Graduate Institute of Environmental Engineering at National Taiwan University, along with Professor Yi-Pin Lin from the same institute and Professor Wen-Che Hou from the Department of Environmental Engineering at National Cheng Kung University, developed a revolutionary gas exchange device coupled with an inductively coupled plasma mass spectrometry (GED-ICP-MS) system that can detect trace metal concentrations in ultrafine particles every five minutes.
This represents a significant improvement over conventional filter-based sampling methods, which typically require 24-hour collection periods and only provide averaged daily concentrations.
Beyond improving scientific understanding, this high-resolution monitoring capability opens new possibilities for real-time air quality alerts and pollution event prediction, potentially enabling public health authorities to issue timely warnings when toxic metal concentrations spike during rush hours or other high-risk periods.
"Previously, we were like watching fast-changing phenomena in slow motion," explains Professor Hsiao.
"Traditional 24-hour sampling dilutes pollution peaks through averaging, obscuring the actual exposure concentrations that people experience during rush hours. Our real-time system finally allows us to see the true picture of pollution events as they happen."
Of particular interest was the analysis of toxic metal sources, which revealed the significant contribution of non-exhaust emissions to health risks. While vehicle exhaust has long been recognized as a major pollution concern, the study found that brake pad and tire wear particles also play an important role in urban air toxicity.
The team identified that these "non-exhaust emission sources" generate heavy metals, including cobalt and nickel, which account for 56% of total health risks, despite contributing less to the particle surface area.
The research brings new perspectives to electric vehicle promotion policies worldwide. While electric cars eliminate exhaust emissions, the study reveals that brake and tire wear problems persist regardless of vehicle type.
"Even in a fully electrified future, we will still need stricter regulations on heavy metal content in brake pad materials and tire composition," notes Professor Hsiao.
The findings suggest that current pollution control strategies, which focus primarily on exhaust emissions, may be missing a significant piece of the puzzle.
More information: Li-Ti Chou et al, Real-time assessment of PM1.0-bound trace metal cancer risk through high-resolution GED-ICP-MS and integrated ELCR analysis, Journal of Hazardous Materials (2025). DOI: 10.1016/j.jhazmat.2025.138711
Journal information: Journal of Hazardous Materials