You are stopped at a light, feet down, and the exhaust pipe of the car beside you sits roughly level with your chin. Your visor is cracked open because it is 33°C and the air inside your lid has stopped moving. This is the moment a helmet filter has to earn its money — and it is the exact moment a vented helmet does least, because a vent is a ram-air device and you are doing 0 km/h. When researchers instrumented ten delivery riders across Bangkok and Chiang Mai for seven months, the riders averaged 133.8 µg/m³ of PM2.5 during peak periods while the static reference sensors nearby read 88.1 (MobileSense, ACM COMPASS '25). Below are the ten questions riders actually search before trusting a filter on their head — including the two the product pages skip.
The short version
- Instrumented delivery riders in Bangkok and Chiang Mai averaged 133.8 µg/m³ of PM2.5 at peak while the static reference sensors beside them read 88.1 µg/m³ — the rider breathes about 52% more than the number on the air-quality map (MobileSense, ACM COMPASS '25).
- No motorcycle helmet standard requires air filtration: neither ECE 22.06 nor DOT/FMVSS 218 contains an air-quality clause, so a helmet's vents exist for thermal comfort and visor demisting only.
- Airflow through a passive vent scales with dynamic pressure (½ρv²), so it collapses quadratically as you slow — it delivers least at the red light, which is where a rider's exposure peaks.
- 133.8 µg/m³ is 8.9× the WHO 24-hour PM2.5 guideline of 15 µg/m³ — and on fleet growth alone, rider-hours above that guideline rise about 38% by 2031 even if the air never gets worse.
A Ten-Year-Old Idea That Still Barely Ships
Q1. What is a helmet filter, and does my helmet already have one?
No, it does not. A helmet filter is an added filtration stage that cleans the air reaching your breathing zone. The vents moulded into your lid are not that. Neither ECE 22.06 nor DOT/FMVSS 218 contains any air-quality requirement — those standards govern impact, retention and visor optics. Vents exist to move heat and clear a fogged visor. We took that question apart in full in do motorcycle helmets have air filters.
Q2. Isn't the mesh behind my vent a filter?
No. PM2.5 means particles 2.5 micrometres and smaller; the insect screen behind a vent is a millimetre-scale grid, roughly a thousand times coarser. Capturing particles at that size is an electrostatic-and-diffusion problem, not a sieving one — which is why filter media is rated by capture efficiency rather than hole size. The media in an Easi Breezi unit is H11, rated ≥95% at PM2.5. The grade question — H11 against H13 against activated carbon — has its own post: HEPA filter for a motorcycle helmet.
Q3. Can I actually buy a helmet filter today?
Mostly not, and this is the category's real problem. The idea is a decade old — WO2016079606A1, "Motorcycle helmet with inbuilt air filtration system", was published in 2016. Shellios shipped Puros in India in September 2022 at about ₹4,500 (~US$56), USB-rechargeable, with independent testing showing over 80% reduction in pollution exposure (New Atlas) — but it is certified to Indian helmet standards, so a European or Southeast Asian rider cannot simply buy one. Zyon, which briefed MCN and New Atlas in September 2025 promising mid-2026 delivery, currently states "Ships Q1 2027" on its own pre-order page — six to nine months later than the date it briefed. We costed that helmet line by line in the Zyon helmet price teardown.
The Four Answers the Product Pages Skip
Q4. Does a helmet filter still work when I am stopped at a red light?
This is the question that separates the approaches, and it is the first awkward answer. A passive vent does almost nothing at a standstill. Airflow driven by forward motion scales with dynamic pressure, ½ρv² — halve your speed and you quarter the pressure driving air through the vent. At 0 km/h there is no ram pressure at all, only whatever convection your body heat manages. As r-pur notes, pollutants at low speed linger at face level rather than being swept past. So the protection fades exactly as the exposure peaks. A powered unit does not have this dependency: the fan sets the flow rate, so a standstill is the same as 60 km/h.
Why the vent quits at the light
Side view, rider stationary in traffic. Illustrative — depicts a mechanism, not measured data.
Because vent airflow scales with dynamic pressure (½ρv²), a passive helmet vent delivers least air exactly when a rider is stationary in traffic — the point at which pollutants linger at face level rather than being swept past (r-pur).
Q5. So is a vented helmet worse than a sealed one in traffic?
In dirty air, sometimes yes — and this is the second awkward answer. Vent geometry is designed to channel the intake stream at the rider's face, because that is what makes a helmet feel cool. In clean air that is comfort engineering. In a queue of exhausts it is a targeted delivery system pointed at your mouth. That does not make sealing up the answer either; a sealed lid in the tropics becomes a heat problem instead, which we measured in do motorcycle helmets get hot. The resolution is filtered airflow rather than a choice between hot and dirty.
Q6. Why does my air-quality app never match how riding feels?
Because the app is reporting a rooftop monitor and you are in the plume. The MobileSense study is the clearest measurement of that gap: ten riders instrumented across Bangkok and Chiang Mai from November 2023 to May 2024, averaging 133.8 µg/m³ at peak against the reference sensors' 88.1 µg/m³. Individual readings ranged from 20.01 µg/m³ to 3,708 µg/m³. Hazard-quotient scoring put six of the ten riders above 1.0, the threshold for elevated chronic risk, with a worst case of 1.92.
What a commute actually costs you
Pick the number you want to believe, then set your daily riding time.
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| Source | PM2.5 (µg/m³) |
|---|---|
| Rider, measured peak average (MobileSense) | 133.8 |
| Static reference sensor, same period | 88.1 |
| WHO 24-hour guideline | 15 |
At the measured rider average of 133.8 µg/m³, an hour of daily riding puts roughly 200 micrograms of PM2.5 through the lungs per day, and H11 media rated ≥95% at PM2.5 removes about 95% of it. Illustrative model: dose = concentration × hours × 1.5 m³/h ventilation rate at light exertion; concentrations from MobileSense, ACM COMPASS '25 and the WHO air quality guidelines.
Q7. Will a filter unit fog my visor?
The mechanism runs the other way. Fogging is condensation — warm, humid exhaled breath meeting a visor that is cooler than the dew point of that breath. Moving air across the inside of the visor carries the moisture away before it condenses, which is precisely why helmets have chin vents at all. A unit that supplies air continuously rather than only when you are moving keeps that airflow at the light, where sealed-up visors normally mist over. This is mechanism rather than a lab measurement, so treat it as a reason to expect improvement, not a specification.
Q8. Does it need charging?
No, and this is a genuine fork in the category. The Easi Breezi unit is vehicle-powered — there is no battery, nothing to charge, and nothing to remember before a ride. Shellios' Puros is USB-rechargeable, which means a flat unit is an unfiltered ride. Sealing matters too: the EB unit is rated IP67 and the design is patent pending.
Projecting to 2031: The Fleet Grows Even If the Air Does Not
Q9. Is this going to get better on its own?
Not on a timescale that helps you. Here is a calculation you can check rather than a forecast you have to trust. Hold the air constant — take the measured Bangkok peak-season rider average of 133.8 µg/m³, already 8.9× the WHO 24-hour guideline of 15 µg/m³, and assume it never worsens. Now apply the two-wheeler market's forecast 6.63% CAGR through 2031 — US$128.71bn in 2026 to US$177.42bn by 2031 (Mordor Intelligence). Since 1.0663⁵ = 1.379, rider-hours spent above the WHO guideline rise about 38% by 2031 on fleet growth alone. If concentrations also drift upward, 38% is the floor rather than the estimate.
(That projection is synthesised here from two sourced inputs — a measured concentration and a published market CAGR — and is labelled as such. It is not a published forecast.)
Regionally the pressure is higher, not lower: the ASEAN two-wheeler rental market is forecast to grow from US$2.04bn in 2026 to US$2.74bn by 2031 (Mordor Intelligence). Electrification does not rescue the rider on this timeline either — you still sit in other people's exhaust, and the haze driving the worst days is not a tailpipe problem at all. On 11 August 2026 IQAir flagged Kuching at AQI 171, the most polluted major city in the world that day, from transboundary peatland fires; Bali's own fires have kept PM2.5 elevated through this week. Six of the world's thirty most-polluted major cities are in Southeast Asia (phys.org, May 2026).
What You Can Actually Buy Today — and What It Costs to Run
Q10. Can I fit one to the helmet I already own, and what does it cost to run?
Yes to the first. Easi Breezi clips to your existing helmet, so your fit, your certification and your visor are unchanged — there is no new lid to buy and nothing to re-certify. The failures above are all the same failure: passive vents depend on speed, and a rider's risk peaks when speed is zero. EB replaces the dependency rather than tuning it. A vehicle-powered fan pulls air through H11 media rated ≥95% at PM2.5 and delivers it to the breathing zone at a constant rate, at 60 km/h and at a standstill alike.
On running cost, the arithmetic is public. EB filter packs are $3.50 for 10, $9.50 for 30 and $15.00 for 50 — thirty cents a filter at the 50-pack. Set that against the alternative: Zyon lists €799 retail, €639 pre-order, ships Q1 2027, and includes twelve filters at roughly one month of daily use each, after which replacements are on you. The unit price is the headline number, but the filter cadence is the one you pay forever, and it is the number the category tends not to publish.
If you want the comparison against the other things riders reach for, we ran masks against active filtration in the ceiling is the seal, the dusty-trail case in best off-road helmet dust filter, and the respirator line in air filter helmet.
Ready to Breathe Cleaner on Every Ride?
Ten questions, ten straight answers — including the two that are awkward for everyone selling in this category, us included. If your eleventh question is when can I have one, pre-orders are open at $199.00, and the first 500 include ten free filters.
Pre-order the Easi Breezi unit — H11 HEPA media rated ≥95% at PM2.5, IP67, vehicle-powered with no battery to charge, patent pending, and it clips to the helmet already in your hallway.
Written by Ash — mechanical engineer and founder of Easi Breezi, building an active HEPA filtration system for motorcycle helmets (patent pending). Based between Hong Kong and Bali, riding daily in the traffic this blog writes about.