You are stopped at a light in traffic, and your head sits at roughly the same height as the exhaust pipe of the car beside you. Across Southeast Asia, riders in that identical position are now experiencing four completely different trends: Indonesia's annual fine-particle average fell 16% in 2025, while Hanoi recorded its sixth consecutive year of rising pollution (IQAir World Air Quality Report 2025). The regional haze story that everyone tells — one season, one problem, one direction — has quietly stopped being true. Which country you ride in now matters more than which month you ride in.
Key takeaways
- Indonesia's annual PM2.5 average fell from 35.5 µg/m³ in 2024 to 30 µg/m³ in 2025, a 16% improvement — and still six times the WHO guideline of 5 µg/m³ (IQAir World Air Quality Report 2025; WHO).
- Vietnam moved the other way, finishing 2025 at 29.7 µg/m³ as the region's second most polluted country, with Hanoi rising for a sixth consecutive year (IQAir 2025).
- Measured black carbon on motorcyclists in Hanoi traffic reached 29.4 µg/m³ against 10.1 µg/m³ for bus commuters on the same roads — roughly 2.9 times the bus figure (Quang et al., Atmospheric Environment, 2021).
- If Indonesia repeated its best year on record every year from 2025, it would not reach the WHO guideline until the mid-2030s.
What does the 2025 data actually say about motorcycle air pollution?
It says the region stopped moving as one. Four neighbouring countries posted four different trajectories in the same year, and the gap between them is now wider than the gap between seasons.
Here is the picture, using each country's annual mean concentration of PM2.5 — the fine particles small enough to stay suspended in the air you ride through.
Indonesia peaked at 51.7 µg/m³ in 2021 and fell to 42 µg/m³ by 2023 (Assessing and Predicting Air Pollution in Asia, arXiv:2501.15590), then to 35.5 µg/m³ in 2024 and 30 µg/m³ in 2025 — a 16% fall in a single year, the strongest in the regional dataset. It remains Southeast Asia's most polluted country (IQAir 2025, via VnExpress International).
Vietnam went from 34.1 µg/m³ in 2021 to 32.9 µg/m³ in 2023 (arXiv:2501.15590) and 29.7 µg/m³ in 2025, taking second place regionally — with Hanoi specifically rising for a sixth straight year (IQAir 2025).
The Philippines ran at 13.5 µg/m³ in 2023 and 14.82 µg/m³ in 2024, then jumped to 19 µg/m³ in 2025, a 28% single-year rise (IQAir 2025; IQAir Philippines). One honest caveat belongs with that number: monitoring coverage expanded over the same period — Quezon City alone added 40 non-reference sensors and one reference station — so part of a jump like this is a network that started seeing hotspots earlier datasets missed. The rise is real. It is also partly the sound of somebody switching a light on.
Thailand has been comparatively flat, moving from 23.3 µg/m³ in 2018 to 26.4 µg/m³ in 2023 (arXiv:2501.15590).
For context on all four: only around 14% of cities worldwide met the WHO annual guideline in 2025 (IQAir 2025).
Four countries, four directions (2021–2025), with one projection to 2031
Annual mean PM2.5, µg/m³. Solid lines are measured. The dashed orange line is our own projection, not a forecast anyone published.
| Year | Indonesia | Vietnam | Philippines |
|---|---|---|---|
| 2021 | 51.7 | 34.1 | not stated |
| 2023 | 42 | 32.9 | 13.5 |
| 2024 | 35.5 | not stated | 14.82 |
| 2025 | 30 | 29.7 | 19 |
| 2031 (projected, our calculation) | 10.5 | not projected | not projected |
Why doesn't a falling national average show up on your ride?
Because a national annual mean and a rider's lungful of air are measuring two different things, and only one of them is you.
A country average is assembled from fixed monitoring stations, most of which are sited to represent background or city-wide air. They are not sited in the half-metre of road where a rider sits in stopped traffic, level with the tailpipes of everything around them. A national figure can fall while that specific half-metre does not move at all — the two numbers are not in contradiction, they are simply not the same measurement.
The rider-specific data makes the gap concrete. Measured black carbon on motorcyclists riding in Hanoi traffic reached 29.4 µg/m³, against 10.1 µg/m³ for bus commuters on the same roads — roughly 2.9 times the bus figure (Quang et al., Atmospheric Environment, 2021). A separate intermodal study found motorcyclists at 33.96 ppb BTEX and 27.65 µg/m³ PM2.5, against 20.07 ppb and 23.27 µg/m³ for cyclists on comparable routes (Environmental Monitoring and Assessment, 2023).
Where the measurement happens SCHEMATIC
Illustrative diagram of siting, not measured data.
That third point is the one riders feel. Passive vents work by ram air: they need forward motion to move anything. Stopped traffic is exactly where the concentration is highest and the airflow through your helmet is lowest, at the same moment.
When does the air actually become clean at this rate?
Not this decade — and that answer holds even if you assume the best case anyone in the region has actually delivered.
Take Indonesia's 2025 result, the strongest single-year improvement in the dataset: 30 µg/m³, down 16% year on year. Compound that same rate forward, every year, without a single haze season going the wrong way:
30 × 0.84ⁿ = 5 → n = ln(5/30) ÷ ln(0.84) ≈ 10.3 years
That lands in the mid-2030s. This is our own arithmetic, not a published forecast — we are stating the working so you can check it. And it is deliberately generous: it assumes a country repeats its best year on record annually for a decade. Vietnam's trajectory points the other way entirely, and Hanoi's six-year climb is the counter-example sitting inside the same dataset.
The published modelling agrees on the direction of the constraint. CMIP6-based projections of surface PM2.5 across Asia show declines arriving around 2030 only under strong emission-control scenarios, with weak-control pathways diverging (Evaluation and Projection of Surface PM2.5 and Its Exposure on Population in Asia Based on the CMIP6 GCMs).
Single seasons still swing hard in the meantime. Malaysia has been dealing with its worst transboundary haze in years across July and August, driven by fires in Sumatra and Kalimantan — a reminder that an annual average is a summary, not a description of any particular morning.
The practical conclusion for a rider is unglamorous but useful: every rider on the road today will spend the rest of this decade riding in air above the WHO guideline, in all four of these countries, regardless of which direction their national line is pointing.
What can a rider actually change?
Not the national trend, and not the traffic. What is available is the air moving through your own helmet — which is the one variable in this article that sits within arm's reach.
Easi Breezi is a modular unit that draws air through a filter and delivers filtered air into your helmet. It gives you powered airflow you can feel, for hot, dusty, traffic-heavy riding, and it runs off your motorbike — no battery to charge. The filter is an H11 cartridge, with filter media tested to 95% at MPPS when new; replace weekly.
One piece of physics worth stating plainly, because it is easy to assume otherwise: a helmet is not a sealed system. Powered filtration delivers dilution of the air around you, not a separate supply of air.
Frequently Asked Questions
Which Southeast Asian country has the worst motorcycle air pollution?
Indonesia recorded the region's highest annual mean PM2.5 in 2025 at 30 µg/m³, six times the WHO guideline of 5 µg/m³, despite improving 16% year on year. Vietnam was second at 29.7 µg/m³ (IQAir World Air Quality Report 2025).
Is air quality in Southeast Asia getting better or worse?
Both, depending on the country. Indonesia and Thailand improved or held roughly steady through 2025, while Vietnam and the Philippines rose — Hanoi for a sixth consecutive year. Treating the region as a single trend no longer reflects the data.
Why is a motorcycle worse than a bus for pollution exposure?
Riders sit inside the traffic stream with no enclosure, at roughly the height of surrounding exhaust outlets. Measured black carbon on Hanoi motorcyclists was 29.4 µg/m³ against 10.1 µg/m³ for bus commuters on the same roads — about 2.9 times the bus figure (Quang et al., 2021).
Does a national air quality average tell me what I breathe on my commute?
Not closely. National means are built from fixed monitors sited to represent background or city-wide conditions, not the roadside position a rider occupies. A national figure can fall while roadside exposure stays flat.
When will Southeast Asian air meet the WHO guideline?
On current evidence, not this decade. Compounding Indonesia's best recorded year of improvement (16%) forward from 30 µg/m³ reaches the 5 µg/m³ guideline in roughly 10.3 years — the mid-2030s — and that assumes an unbroken run of best-ever years.
Ready to Change the One Variable You Control?
The national trend in your country is not something you can move this year. The air moving through your helmet on tomorrow's commute is. Easi Breezi is available to pre-order now at $199.00.
Pre-order the Easi Breezi unit
Written by Ash — mechanical engineer and founder of Easi Breezi, building an active H11 filtration system for motorcycle helmets (patent pending). Based between Hong Kong and Bali, riding daily in the traffic this blog writes about.