You are stopped at the lights, one foot down, still breathing hard from the last three hundred metres. The motorcyclist beside you is sitting still, breathing normally, in the same cloud of exhaust. You are moving 23.5 litres of air a minute through your lungs; they are moving about 11.8 (Zuurbier et al., Environmental Health, 2009). That gap is the whole answer to whether an air purifier for cyclists can do anything for you — and almost nobody selling one will mention it.
The short version: a purifier cleans a volume of air. Your problem is the dose reaching your lungs, and dose depends on how hard you are breathing. Change the breathing rate and you change the exposure, whatever the purifier is rated at.
The short answer
- Cyclists move an average of 23.5 litres of air a minute, against 11.8 litres for a car passenger and 12.7 on a bus — a ratio of 2.09 to the car, measured across 34 people (Zuurbier et al., Environmental Health, 2009).
- On routes with climbs, cyclists' ventilation ran 4.3 times the rate of car drivers and their inhaled pollutant dose 4 to 9 times as high (Lathouwers et al., Journal of Transport & Health, 2021).
- Wearable ionizer "purifier" necklaces removed under 10% of PM2.5 in chamber testing, against roughly 95% for a properly fitted mask (Smart Air).
- Motor-scooter riders sit in higher PM2.5 concentrations than cyclists, across a review of 52 studies — so the cyclist's lower concentration is partly cancelled by their higher breathing rate (Journal of Cycling and Micromobility Research, 2025).
Do cyclists breathe more pollution than motorcyclists?
Not more pollution in the air — more air. And that is the distinction every product page skips.
Two things are true at once, and they pull in opposite directions. Riders on motor-scooters sit in higher PM2.5 concentrations than cyclists, according to a 2025 scoping review of 52 studies in the Journal of Cycling and Micromobility Research — seven of which made direct bicycle-versus-motor-scooter comparisons, five of them in Asia. Scooters sit lower in traffic, closer to tailpipes, and move with the exhaust stream rather than through it.
But the cyclist is working. The Zuurbier study put respiratory monitors on 34 people and found cyclists averaging 23.5 L/min, against 11.8 L/min in a car and 12.7 L/min on a bus — a ratio of 2.09 to the car and 1.99 to the bus. On hillier routes the effect is larger still: Lathouwers et al. (2021) measured ventilation at 4.3 times the rate of car drivers on the same route, and an inhaled dose of black carbon, NO₂, PM2.5 and PM10 running at 4 to 9 times as much.
One honest caveat, because it matters: no published study I can find measures a motorcyclist's minute ventilation directly. A motorcyclist is seated and not exerting, so the car and bus figures (11.8–12.7 L/min) are the closest available stand-in — a reasonable proxy, but a proxy, not a measurement. Treat every motorcyclist number below as that.
What does dose actually depend on?
Three terms, multiplied:
Dose = concentration × ventilation rate × time.
A purifier only acts on the first term, and only inside a volume it can actually service. Your breathing rate sets the second. The length of your commute sets the third. Get any one of them wrong and the answer is wrong.
Run the numbers yourself:
Your commute, both ways round
Pick a country's 2025 average PM2.5, set your ride length, and compare inhaled mass at a cyclist's breathing rate against a seated rider's.
—
| Mode | Ventilation | Inhaled PM2.5 |
|---|---|---|
| Cycling | 23.5 L/min | 31.7 µg |
| Seated rider | 11.8 L/min | 15.9 µg |
Illustrative model: inhaled mass = concentration × (litres per minute ÷ 1000) × minutes. Concentrations are 2025 national annual averages from the IQAir 2025 World Air Quality Report; ventilation rates from Zuurbier et al. (2009). Both modes are held at the same concentration here — in reality the scooter rider's concentration is the higher of the two, which narrows the gap further.
At Indonesia's 2025 national average of 30 µg/m³ (IQAir), a 45-minute ride puts roughly 31.7 µg of PM2.5 into a cyclist and 15.9 µg into a seated rider at the same concentration. Then correct for the fact that the scooter rider's air is dirtier, and the two converge. Which is the point: this is not a question with a winner. It is a question about which term you can actually change.
Why can't a purifier reach you?
Because there is no boundary for it to work across.
At 23.5 L/min you pull about 1.41 cubic metres of air an hour through your lungs. An open-air wearable has no sealed volume to clean and no way to keep pace with that. Smart Air tested wearable ionizer necklaces in a 0.46 m³ chamber and measured under 10% PM2.5 reduction — their summary is blunt: "10% protection isn't great, and far lower than the 95% protection you get from wearing a mask."
The failure is geometric, not electrical. A filter's rating describes what happens to air that crosses the medium. If air can reach your face without crossing it, the rating is irrelevant to your dose. It is the same reason helmet vents filter nothing: they define a path for air, not a barrier. It is also why where you sit in traffic changes what you breathe.
Will cleaner cities fix this?
Not the part that matters to you.
Ambient air is currently moving the wrong way. Only 14% of global cities met the WHO annual PM2.5 guideline of 5 µg/m³ in 2025, down from 17% the year before, and 92.5% of countries exceeded it (IQAir 2025 World Air Quality Report). Across Southeast Asia in 2025, Indonesia averaged around 30 µg/m³ — roughly six times the guideline — and Vietnam 29.7 µg/m³, or 5.9 times it. Thailand and Cambodia each sat about 3.6 times above, Myanmar 4.7 and Laos 4.5.
Here is the projection worth holding on to, and it is ours rather than a cited forecast: the ventilation multiplier is physiology, not policy. A 2.09× breathing-rate gap does not shrink when a city electrifies its fleet. It is set by human effort. So as concentrations fall over the next five years — and they may — the relative penalty carried by the exercising rider stays roughly where it is. Two of the three terms in the dose equation are outside your control on any given morning. The third, the path air takes to your face, is the only one you can engineer.
Worth noting too: that 2025 review flagged how thinly the Global South is represented in the exposure literature — which is precisely where two-wheelers dominate. The measured picture is probably an underestimate for the cities EB riders actually live in.
So what is worth buying?
Match the tool to the term you are trying to change.
- A wearable "purifier" necklace changes almost nothing — under 10% measured. Skip it.
- A well-fitted mask works on the concentration term and reaches roughly 95%, but it fights you at 23.5 L/min. Breathing resistance is the trade, and it is a real one on a bike.
- A defined, filtered intake is the only approach that lowers concentration at the airway without adding resistance to every breath — because a fan does the work instead of your lungs.
That last one is what Easi Breezi is. The unit mounts to the helmet and drives filtered air into the shell, so the air arriving at your face has crossed the filter medium rather than merely passed near it — a positive-pressure intake path instead of an open-air cleaner. The filter captures ≥95% of PM2.5.
Being straight about the fit: it is a motorcycle-helmet system. A full-face shell gives it a volume to pressurise. An open bicycle helmet does not, and no amount of engineering changes that geometry — which is exactly the honesty the rest of this post is built on. If you ride a scooter or a motorcycle through the same traffic, it applies directly; we covered the neighbouring case in air purifier vs scooter, and the wider gear landscape in our anti-pollution gear comparison.
Frequently Asked Questions
Is there a good air purifier for cyclists?
Not in the wearable form most people mean. Devices small enough to clip or hang have no sealed volume to service and measured under 10% PM2.5 reduction in chamber testing. Route choice, timing, and a well-fitted mask do more for a cyclist's dose than any wearable purifier currently sold.
Do cyclists breathe more pollution than drivers?
They breathe more air — 23.5 L/min against 11.8 in a car, a ratio of 2.09 (Zuurbier et al., 2009). Concentration is often lower for cyclists, so the total inhaled dose depends on the route. On hilly routes, measured inhaled dose ran 4 to 9 times as high as car drivers'.
What is the difference between a bicycle and an air purifier in exposure terms?
A purifier lowers the concentration inside a defined volume. A bicycle raises your ventilation rate. Because dose is concentration multiplied by ventilation multiplied by time, the two act on different terms — which is why owning a purifier at home changes nothing about your commute.
Does a helmet filter work for cycling?
An active filtration unit needs an enclosed shell to pressurise, so it suits full-face motorcycle helmets rather than open bicycle helmets. The underlying principle still holds for cyclists: only air forced through a medium is filtered air.
How much does the Easi Breezi unit cost?
The EB unit is $199.00. There is no active discount code. For the current shipping date, check the product page.
Ready to Breathe Cleaner on Every Ride?
If you ride a motorcycle or scooter through traffic, the one term in the dose equation you can actually control is the path air takes to your face. Easi Breezi gives it one way in, through a filter that captures ≥95% of PM2.5, without asking your lungs to pull against a mask.
See how a defined intake path changes the maths → — $199.00.
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.