Air quality across Asian cities is improving – but not at the pace required, and not consistently across the region.
At the Better Air Quality (BAQ) Conference 2026 in Bangkok, a clear tension emerged. While long-term pathways such as electrification and public transport are critical, they will take time to scale – particularly in markets where infrastructure, affordability and enforcement remain uneven.
At the same time, vehicular emissions remain a significant contributor to urban air pollution, with heavy-duty vehicles and ageing fleets continuing to dominate in many cities. Most vehicles currently on the road will remain in operation for decades.
This shifts the focus to a more immediate question: What can reduce air pollution today?
Ether-based oxygenated fuels can.
Unlike large-scale system changes, improvements in fuel composition can be implemented within existing supply chains and deliver immediate impact across in-use vehicles. This is particularly relevant in markets where vehicle turnover is slow.
A recent study by the Bandung Institute of Technology (ITB) confirms that the type of blending components used in fuel has a significant influence on motor vehicle pollution levels. The study applied the US Environmental Protection Agency’s Motor Vehicle Emissions Simulator (MOVES) to evaluate real-world pollutant emissions across different gasoline formulations in Jakarta and Surabaya.
Professor Puji Lestari, one of the researchers involved in the study, stated, “Our analysis confirms that including oxygenates reduces harmful pollutants, particularly when using ethers. This can significantly improve air quality in dense urban environments such as Jakarta and Surabaya,” as she noted at BAQ 2026.
The findings show that fuel composition plays a critical role in shaping pollution outcomes. In particular, ether-based oxygenates such as MTBE and ETBE were found to deliver stronger reductions in key pollutants, including carbon monoxide (CO), particulate matter (PM2.5) and other air toxics, compared to alternative blends under certain operating conditions.
Performance also varies depending on the type of oxygenate used, reinforcing the need to assess fuel pathways based on pollution reduction rather than blending targets alone.
Discussions at BAQ also highlighted that improving urban air quality requires addressing a broader set of structural challenges beyond fuel.
Participants pointed to the continued import of older and high-emitting vehicles as a key constraint, with gaps in vehicle standards undermining the effectiveness of cleaner fuel policies. In parallel, the need for stronger data integrity and consistency was emphasised, as policymakers increasingly rely on real-time monitoring, sensors and open-source datasets to inform decision-making.
There was also growing recognition that vehicular emissions are only part of the problem. Non-exhaust sources – including tyre and brake wear – as well as emissions from industrial activity, construction and residential fuel use, are becoming increasingly important contributors to urban air pollution.
Heavy-duty diesel vehicles remain a major concern across many markets, reinforcing the need for a coordinated approach that aligns fuel quality, vehicle standards and broader air quality management strategies.
This points to the need for a more coordinated approach to improving urban air quality across the region.
Fuel quality, vehicle standards and data systems cannot be addressed in isolation. Gaps in any one area – whether through inconsistent enforcement, ageing vehicle fleets or poor data quality – can limit the effectiveness of otherwise well-intentioned policies.
Experience from more advanced markets shows what this coordination can achieve. In Seoul, sustained improvements in air quality have been supported by tighter fuel sulphur standards, stricter vehicle emissions controls, and active in-use vehicle monitoring. Similarly, China’s progressive tightening of fuel quality standards, combined with vehicle regulations and enforcement measures, has contributed to measurable reductions in particulate pollution across major cities.
In addition, European cities such as London have demonstrated how coordinated measures, including cleaner fuel standards, low emissions zones and stricter vehicle requirements, can accelerate improvements in urban air quality when implemented together.
These examples highlight a consistent lesson: improvements in fuel quality are most effective when implemented as part of a broader, aligned policy framework.
For policymakers across Asia, the priority is therefore not to rely on a single intervention, but to deploy practical measures that deliver measurable reductions in harmful pollutants under real-world conditions.
In that context, improving fuel quality remains a scalable and immediately deployable part of that solution.
For access to the full MOVES study and supporting findings, please contact Asian Clean Fuels Association (ACFA) at info@acfa.org.sg.
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