If you have shopped for a HEPA filter for a motorcycle helmet, you have seen the word "HEPA" printed on a box and almost nothing else. No grade. No airflow figure. No pressure drop. Meanwhile the car stopped next to you at the lights now ships with a filtration spec you can actually read.
Key takeaways
- Under EN 1822, an H13 filter must capture at least 99.95% of particles at the most penetrating particle size, while the 95% class listed as H11 sits below it, so a box marked only "HEPA" tells a rider nothing (MANN+HUMMEL).
- Higher filter grades cost airflow: an H13 filter runs an initial pressure drop of roughly 200 to 250 Pa at rated airflow, and H14 climbs to 300 to 350 Pa or higher (AiryFilter).
- Activated carbon adsorbs gases, odours and VOCs but does not capture particulate, and HEPA media captures particulate but does not remove VOCs, so the two are stages in a stack rather than competing choices (Oransi).
- Indonesia's annual average PM2.5 fell from 40.7 µg/m³ in 2020 to 30.0 µg/m³ in 2025, a 26% improvement that still leaves the air six times the WHO annual guideline of 5 µg/m³ (IQAir).
Which HEPA filter grade is best for a motorcycle helmet?
For a helmet-mounted unit running on a battery, the honest answer is that the highest grade is not automatically the best one. What protects you is not single-pass efficiency alone. It is efficiency multiplied by the volume of air the fan can actually pull through the media. Raise the grade and you raise the resistance, and in a small sealed unit with a fixed fan, the flow falls. A filter that captures a slightly smaller share of a much larger volume of air can deliver more clean air to your face than a laboratory-grade filter the fan is struggling to breathe through.
That tradeoff is standard practice in filtration engineering. It is almost never explained to riders.
The air got better. Your dose did not.
Start with the thing most rider content gets wrong by omission: the ambient air in Southeast Asia has genuinely been improving.
Indonesia's annual average PM2.5 ran at 40.7 µg/m³ in 2020, 34.3 in 2021, 30.4 in 2022, 37.1 in 2023, 35.5 in 2024 and 30.0 in 2025, according to IQAir's country series. That is a 26% fall across five years. IQAir also recorded the 2024 figure of 35.5 µg/m³ as a 4% decrease on 2023.
Indonesia annual average PM2.5, 2020 to 2025
Against the WHO annual guideline of 5 µg/m³. All points measured, no forecast.
| Year | PM2.5 |
|---|---|
| 2020 | 40.7 |
| 2021 | 34.3 |
| 2022 | 30.4 |
| 2023 | 37.1 |
| 2024 | 35.5 |
| 2025 | 30.0 |
| WHO annual guideline | 5 |
Six times the guideline, after five years of improvement. A national annual mean moving a few micrograms does not change what you inhale at a red light with a bus idling in front of you. The variable you actually control is the filter. Which is why the filter's spec deserves a harder look than it usually gets.
Why the highest filter grade is the wrong answer in a helmet
The grades are not interchangeable, and the naming is a mess
Under EN 1822, H13 is rated at 99.95% or better at the most penetrating particle size, and H14 at 99.995% or better (MANN+HUMMEL, Clean Air Technology).
The 95% class sits below that. It appears as H11 with a 95% overall value in the EN 1822 table reproduced by ScienceDirect, and is classified as E11 at 95% or better in the current revision's EPA group. H11 and E11 describe the same 95% performance floor under different naming conventions. One filtration supplier puts the practical gap plainly: H13 captures 99.95% against 95% for H11, which means roughly five times fewer particles pass through per pass.
So when a product says "HEPA" and stops there, it could mean either. Ask for the class.
MPPS is not 2.5 microns
Riders consistently misread the number downward. A grade is defined at the most penetrating particle size, which Camfil puts in the range of 0.1 to 0.2 microns. That is the hardest particle for the media to catch, not the average one. A filter rated at 95% at MPPS performs better than 95% on the coarser PM2.5 that dominates traffic air. The rating is a floor measured at the worst case.
Grade costs pressure, and pressure costs air
This is the part that changes the answer.
An H13 filter runs an initial pressure drop of roughly 200 to 250 Pa at rated airflow of about 0.45 m/s, with H14 at 300 to 350 Pa or higher. A second supplier puts H13's initial static pressure drop at approximately 150 to 250 Pa. Step down a grade and the resistance drops materially: H12 is cited at roughly 30% less resistance than H13.
A mains-powered box purifier can brute-force that resistance with a bigger fan and more watts. A helmet unit cannot. It runs on a battery, it has to be quiet enough to ride with, and it has to fit on a helmet without turning into a sail. Fix the fan and raise the grade, and the flow collapses. You gain 4.95 percentage points of single-pass efficiency and lose a much larger share of the air volume you were cleaning.
The same logic is why filtration guidance for single-pass devices sometimes favours the lower grade outright. Filter class is not a score. It is one term in a product of two.
Carbon is a different machine entirely
Activated carbon adsorbs gases, odours and VOCs. It does not capture particulate. HEPA media captures particulate. It does not remove VOCs. That is the whole distinction, and it is consistent across filtration sources.
So "HEPA vs carbon" is a false choice. They are two stages solving two problems, which is why OEM cabin systems are described as multi-stage stacks combining HEPA-class media with an activated carbon layer. Carbon also brings its own costs: it adds pressure drop of its own, and it eventually saturates. On a helmet, every millibar of that has to be paid for out of a battery.
Try it against your own commute
Filter grade and your daily PM2.5 dose
Anchored on Indonesia's 2025 annual average of 30 µg/m³ (IQAir). Holds airflow constant, which is exactly the assumption this article is arguing with.
On paper H13 looks a hundred times better than H11, because this model holds airflow constant. In a battery-powered helmet unit it is not constant: raising the grade raises the pressure drop and cuts the volume of air actually cleaned, which is why the real-world gap between the two is far narrower than the labels suggest. Ventilation rate of 1.5 m³/h is illustrative, not measured.
| Filter | Micrograms per day |
|---|---|
| No filter | 45.0 |
| H11 at 95% | 2.25 |
| H13 at 99.95% | 0.02 |
Cars are getting a spec sheet. Riders are getting a sticker.
Look at what the enclosed commuter now gets as standard. A market report published this month documents cabin filtration validated at 99.65% PM2.5 removal in the Mercedes EQS package, 99.9% interception at 0.1 microns in a Toyota Boshoku module, and N95-level cabin filtration as a baseline spec across BYD trim levels, with nanofiber composite media targeting PM0.1 in development for the Euro 7 design window. The same report notes that in-vehicle PM2.5 concentrations frequently exceed ambient levels by a factor of two to four during urban commutes, and that roughly 99% of the global population breathes air above the WHO PM2.5 guideline.
That market was estimated at USD 2.6 billion in 2025 and is projected to grow at an 8% CAGR between 2026 and 2035. Compounding that sourced rate from that sourced base gives roughly USD 4.1 billion by 2031. That is a synthesised figure, not a published forecast, and the arithmetic is 2.6 × 1.08^6.
Here is the part worth sitting with. By 2031 the driver will have filtration measured at PM0.1, published on a datasheet and fitted as standard. The rider, taking a higher dose without the cabin that produced those numbers, will still be buying products labelled "HEPA" with no grade, no pressure drop and no airflow figure printed anywhere on the box.
That is not a technology gap. It is a disclosure gap. And it is the easier of the two to close.
Frequently asked questions
Is H13 better than H11 for a helmet filter?
Per pass, yes: H13 is rated at 99.95% or better at MPPS versus 95% for the H11 class. In a battery-powered helmet unit, not necessarily, because H13's higher pressure drop reduces the airflow the fan can move, and what reaches your face is efficiency multiplied by flow.
Does a HEPA filter remove exhaust fumes and smells?
No. HEPA media captures particulate. Gases, odours and VOCs need activated carbon, which works by adsorption and is a separate stage with its own pressure drop and its own saturation life.
What does "HEPA" on a product actually guarantee?
On its own, very little. Ask for the EN 1822 class. H13 means 99.95% or better at MPPS; the 95% class appears as H11, or as E11 in the standard's current EPA group. A product that will not state a class is asking you to trust a word rather than a number.
Is 95% enough?
The grade is measured at the most penetrating particle size, roughly 0.1 to 0.2 microns, which is the filter's worst case. Real-world performance on the coarser PM2.5 that dominates traffic air is better than the rating. We cover the underlying media physics in HEPA filters explained for motorcyclists.
What should I compare when buying?
Three things, in this order: the EN 1822 class, the airflow the unit actually delivers, and whether it runs when you are stopped. Passive vents fail the third test entirely, which we break down in the helmet air filtration guide.
Ready to breathe cleaner on every ride?
Easi Breezi runs an H11 HEPA filter rated at 95% or better on PM2.5, driven by an active fan rather than a passive vent, and rated IP67. The grade is a deliberate engineering choice, not a cost-down: in a battery-powered helmet unit, a higher class would have bought a slightly better single-pass number at the cost of the airflow that actually carries clean air to your face. Patent Pending.
Pre-orders are USD 199.00. Filters are sold separately in 10-packs.
Three questions to ask any filtration product before you buy: what EN 1822 grade, what airflow, and does it run when you are stopped? See the full spec for the EB unit.
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.