Most people choose an anti-pollution mask by its certification — FFP3, N99 — but a real-world mask test on busy roads tells a dMost people choose an anti-pollution mask by its certification — FFP3, N99 — but those ratings come from controlled lab aerosols, not the diesel soot you actually breathe on a busy road. So researchers at Queen Mary University of London asked a more practical question: tested against real London traffic pollution, how much black carbon does each mask actually block? They compared five masks, including Totobobo, Respro, and an FFP3 (N99) industrial respirator — and the gap between them was large. Totobobo cut black carbon by 71%, the highest of any mask tested.
Why test against real traffic pollution?
Black carbon — the soot in diesel exhaust — is linked to respiratory and cardiovascular harm, and cyclists and pedestrians breathe a lot of it on congested roads. Laboratory filtration ratings are useful, but they’re generated with standardised test particles in a chamber. They don’t tell you how a mask performs against the messy, fluctuating mix of real roadside air.
This study closed that gap by running the test outdoors, in live traffic pollution on busy London streets — using the actual air, not a lab substitute.
How the study was done
It’s worth being precise about the method, because it shapes what the results do and don’t prove.
The researchers tested five masks:
- Totobobo reusable respirator
- FFP3 (N99) industrial respirator
- Respro City Anti-Pollution mask
- Dettol Protect+ (with USB ventilator)
- Surgical mask
Each mask was fitted with an airtight seal to one end of a spacer chamber (an Aerochamber). A researcher breathed through the chamber while standing on the pavement of busy roads in Marylebone and Whitechapel, and an aethalometer (MicroAeth AE51) sampled the black carbon inside the chamber every 30 seconds. Each mask was tested for at least 15 minutes, and the black carbon getting through was compared with the ambient roadside air.
One important consequence of sealing each mask to the chamber: it isolated the filter material. Fit and face-seal were deliberately taken out of the equation, so these results measure how well each mask’s filter removes black carbon — not how well it seals to a face. (More on why that distinction matters below.)
The results: black carbon reduction by mask
Four of the five masks reduced black carbon. The differences were substantial.
| Mask | Black carbon reduction | Statistical significance |
|---|---|---|
| Totobobo | 71% (−2022 ng/m³) | p < 0.0001 |
| FFP3 (industrial) | 44.2% (−1613 ng/m³) | p < 0.0001 |
| Dettol Protect+ | ~42% (−332 to −530 ng/m³) | p < 0.0001 |
| Respro City | 30% (−261 ng/m³) | p < 0.05 |
| Surgical mask | No reduction (slight increase, +2252 ng/m³) | p = 0.05 |
Reduction measured through each mask’s filter versus ambient roadside air, in a sealed chamber test on busy London roads (Marylebone & Whitechapel). Source: Liu et al., Thorax 2017.
A few things stand out:
- Totobobo’s filter removed the most black carbon — 71%, well ahead of the FFP3 industrial respirator at 44.2%.
- A higher certification didn’t guarantee more real-world reduction. The FFP3 (N99) industrial mask blocked less black carbon than Totobobo against actual traffic soot.
- The Dettol Protect+’s USB fan added minimal benefit — turning the ventilator on didn’t meaningfully improve the result.
- The surgical mask didn’t reduce black carbon at all — it trended slightly worse. The researchers suggested condensation from breathing may have impaired the filter.
What the numbers do — and don’t — show
Because every mask was sealed to the test chamber, this study is a clean comparison of filter performance: how effectively each mask’s material strips black carbon out of real traffic air. On that measure, Totobobo came first by a clear margin.
What this particular study does not test is fit — how well a mask seals against a moving, sweating face. That matters enormously in everyday use, because a poorly sealed mask lets unfiltered air leak in around the edges no matter how good the filter is. Fit is a separate question, addressed by separate evidence — Totobobo’s heat-mouldable, custom-fit design and its independent filtration testing (see our filter test reports). The takeaway is that Totobobo performs strongly on both fronts, but this study speaks to the filter, not the seal.
What it means for cyclists and urban commuters
For anyone riding or walking next to traffic every day, the practical lesson is simple: certification labels alone don’t tell you how much real traffic soot a mask will keep out. Against live London pollution, the masks varied from 71% reduction down to none — despite carrying respectable ratings on paper. If reducing black-carbon exposure is your goal, the filter’s real-world performance is what counts, and it’s worth looking past the rating on the box.
Scientific transparency
This research was published as a peer-reviewed conference abstract, not a full-length journal article. Conference abstracts are a standard part of medical research — reviewed for scientific validity, but intentionally concise, and based here on a small set of tests. We think it’s important to be clear about that rather than overstate it. The study was independent and not commissioned by Totobobo.
Citation: Liu NM, Wan T, Russell-Jones EC, Grigg J. Can masks protect you from air pollution? (Abstract P146). Thorax 2017;72(Suppl 3):A162. Available at: thorax.bmj.com/content/72/suppl_3/a162.2
The bottom line
Tested against real London traffic pollution, four of five masks reduced black carbon — but by very different amounts, and the Totobobo mask removed the most, at 71%. Certification is a starting point, not the whole story; how a filter performs against actual diesel soot is what protects your lungs.
➡️ Want to see how this fits into choosing a mask for daily riding — fit, fog, comfort, and cost over time? Read our full guide: Best Cycling Mask for Pollution.