Why Mask Fit Matters

The Science Behind Totobobo

Two Things Determine How Well a Respirator Protects You

People often compare respirators by looking at one number: filter efficiency.

That figure is important, but it tells only part of the story.

Every respirator has two jobs. The filter must remove airborne particles, and the mask must fit closely enough that the air you breathe passes through the filter rather than escaping through gaps around the edges.

This matters in everyday situations, not just in laboratories. A cyclist riding in traffic pollution breathes hard, and any leak around the mask edge lets exhaust particles straight in. An artist working with pastels depends on a good seal to keep fine pastel dust out of the lungs. A parent fitting a mask on a child needs a way to check that the seal actually works on a smaller face.

This distinction is well recognised in occupational respiratory protection. Hospitals routinely fit-test healthcare workers because a certified respirator cannot deliver its intended performance if unfiltered air bypasses it.

In other words, filtration determines what a respirator can remove. Facial fit determines whether the air you inhale actually passes through the filter.

This page brings together independent laboratory testing, university research, and hospital studies related to the Totobobo mask, along with broader research on respirator performance. It includes studies in which Totobobo performed well, as well as earlier studies in which it did less well. The aim is to explain what the available evidence shows, what it does not show, and why understanding both filtration and fit is essential when choosing any respirator.

What This Page Doesn’t Claim

This page does not claim that:

• Totobobo is better than an N95 respirator.
• A highly efficient filter alone guarantees protection.
• One respirator fits every face equally well.
• Careful fitting is unnecessary.

Instead, it summarises published evidence, explains the strengths and limitations of each study, and shows how the findings fit together.

Key Findings about the Totobobo mask

Independent research consistently supports four conclusions:

• Laboratory testing measured 99.86% particle filtration efficiency at 0.1 micron for the Totobobo F96 filter.
• A hospital study found that the newer Totobobo design provided protection comparable to that of professionally fit-tested N95 respirators when properly trimmed and shaped to the user’s face.
• Comfort studies suggest that many users preferred Totobobo over a conventional N95 respirator.

Filtration Is Only Half the Story

Even an excellent filter cannot clean the air that slips through gaps between the mask and the wearer’s face. Any air that bypasses the filter is inhaled without being cleaned. This is why respiratory protection programmes place so much emphasis on quantitative fit testing. The objective is to confirm that the respirator fits the individual wearer closely enough to minimise inward leakage.

Understanding this principle makes it much easier to interpret the research discussed below.

What Respirator Research Has Taught Us – Why mask-fit matters

A landmark study comprising 500 fit tests demonstrated the significance of mask fitting. The large-scale study was conducted by researchers at Tongji University in 2017, who evaluated ten commonly used N95 filtering facepiece respirators on Chinese adults using quantitative fit testing.

The results were striking.

Only 7.8% of respirator–wearer combinations passed quantitative fit testing. More than half of the participants were unable to obtain an acceptable fit with any of the ten respirator models tested, and many believed their respirator fitted well when objective testing showed significant inward leakage.

The study did not conclude that N95 respirators are ineffective. Rather, it reinforced the principle: a high-performance filter can only deliver its intended protection when the respirator fits the individual wearer closely enough to minimise air leakage.

This finding provides important context for understanding the studies that follow. They examine not only how well Totobobo filters particles, but whether its design helps ordinary users achieve a close facial fit.

Why Totobobo Was Designed Differently

Most respirators are manufactured in a limited range of fixed sizes. While this simplifies production, it assumes that a small number of sizes can accommodate the wide variation in human facial sizes and shapes.

Totobobo was developed from a different starting point.

Francis Chu, the inventor and the father of two young children, said:
“My concern was not whether high-performance filter materials existed—they already did. The question was very practical: How could I tell whether a mask was actually fitting my children’s faces properly?”

Professional respiratory protection programmes answer that question with quantitative fit testing using instruments such as the PortaCount. This equipment objectively measures the concentration of particles inside and outside a respirator to determine how well it fits. They are highly effective but also expensive and unavailable to most families.

For everyday users, fitting is often based on experience, a user seal check, or simply how the mask feels. As demonstrated in the Tongji study, none of these methods can quantify protection. An apparently comfortable mask may still allow unfiltered air to enter through small gaps.

That observation shaped the design of Totobobo.

The reusable mask body is made from a thermoplastic material that can be softened in hot water, trimmed if necessary, and moulded to better match the wearer’s facial contours. Just as importantly, the transparent mask body allows users to see how the mask sits against the face while fitting it. Although visual inspection cannot replace quantitative fit testing, it provides practical feedback that opaque masks cannot. Obvious gaps can often be identified, the mask repositioned, or the edge remoulded before use.

The intention was never to replace professional fit testing. It was to give ordinary parents a more practical way to improve the fit of their respirator using visual feedback.

Whether that design approach translates into measurable performance is a question best answered by independent research.

What Independent Research on Totobobo Shows?

Independent Laboratory Testing: Totobobo Filter Performance

The filter material is the easiest part of a respirator to evaluate because it can be tested independently of facial fit.

In 2014, Nelson Laboratories in the United States tested the Totobobo F96 filter using ASTM F2299, a recognised method for measuring particle filtration efficiency.

The challenge particles averaged approximately 0.1 micron, about one-thousandth of the width of a human hair. Of 12,336 challenge particles, only 17 penetrated the filter, giving a measured particle filtration efficiency of 99.86%.

What this tells us

The filter material itself performs extremely well under controlled laboratory conditions.

What it does not tell us

Laboratory filtration tests evaluate only the filter material. They do not measure how well a respirator fits different people or how much unfiltered air may bypass the filter during normal wear.

University Study: Reducing Traffic Pollution

Researchers at Queen Mary University of London want to find out if the masks can perform well beyond laboratory testing. They wanted to find out how effectively different masks reduce exposure to harmful particles when worn in real traffic pollution. 

The researchers compared five commercially available masks using air collected from busy London roads. To neutralise the effects of uncertain facial fit, each mask was connected to the same controlled breathing system so that only the filtration performance could be evaluated.

The pollutant measured was black carbon, a recognised indicator of diesel-related air pollution.

Among five masks tested, Totobobo achieved the greatest reduction in black carbon, lowering concentrations by 71% under the study conditions. 

What this tells us

The study provides independent evidence that the Totobobo filter performs well against traffic-related particulate pollution under controlled conditions.

What it does not tell us

The study was designed to compare filter performance rather than how well different masks fit different people. It was also published as a conference abstract rather than a full peer-reviewed paper, so its findings should be interpreted accordingly.

Hospital Study: Can Users Achieve a Close Fit?

The next question is the one that matters most in everyday use.

Can an ordinary user achieve a facial fit good enough for the filter to perform as intended?

In 2022, researchers Li et al. at the Chinese University of Hong Kong and the Prince of Wales Hospital investigated this by comparing the newer Totobobo design with professionally fit-tested N95 respirators.

Twenty-two volunteers first wore an N95 respirator that had already passed professional fit testing. Each volunteer then fitted a Totobobo respirator as instructed, trimming and moulding it where necessary.

Using a PortaCount quantitative fit tester, the researchers measured the filtration factor for both respirators.

The newer Totobobo achieved a median filtration factor of 84.5, while the professionally fit-tested N95 respirator achieved 77.5. The difference was not statistically significant.

What this tells us

In this study, participants were able to fit the newer Totobobo design well enough for its measured protection to be statistically comparable to professionally fit-tested N95 respirators.

What it does not tell us

The study involved a relatively small number of participants and does not imply that every user will achieve the same result. As with any respirator, careful fitting remains essential.

Earlier Hospital Study of the Totobobo mask

Scientific understanding improves by comparing newer findings with earlier work.

A 2010 study published in the Journal of Hospital Infection evaluated an earlier generation of the Totobobo respirator.

Unlike the later study, the earlier design provided clearly lower protection than professionally fit-tested N95 respirators.

We include this study because it forms an important part of the evidence rather than an inconvenient exception.

Taken together, the two hospital studies suggest that the design evolved substantially over time. They also reinforce a broader conclusion that applies to all respirators: improving facial fit is an ongoing engineering challenge rather than a one-time achievement.

Comfort and Reusability

Protection depends not only on laboratory performance but also on whether a respirator is comfortable enough to be worn consistently.

The 2022 study, therefore, also examined user comfort and the effects of repeated cleaning with 70% ethanol.

Twenty of the twenty-two participants preferred Totobobo to the conventional N95 respirator, particularly around the nose and facial contact area. Repeated cleaning did not produce a significant reduction in measured fit or comfort over fifteen cleaning cycles.

The study also highlighted an important practical point.

Only around 45% of participants achieved an acceptable fit on their first attempt. Many required a second fitting before achieving satisfactory performance.

This finding suggested that even a well-designed respirator benefits from careful fitting and adjustment.

What Can We Reasonably Conclude?

No single study can fully answer how well a respirator performs. Each study examines a different aspect of performance, and each has its own strengths and limitations. Taken together, however, the available evidence presents a clearer picture.

Independent laboratory testing shows that the Totobobo F96 filter has very high particle filtration efficiency under controlled conditions. University research suggests that it performs well against traffic-related particulate pollution. Hospital studies indicate that the newer mould-to-fit design can provide protection comparable to that of professionally fit-tested N95 respirators when properly fitted. Comfort studies suggest that users are generally willing to wear it for extended periods, which is an important consideration for frequent, long-duration use.

At the same time, the research does not support the conclusion that any respirator guarantees protection regardless of how it is worn. Across all of the studies, one principle remains consistent: filtration and facial fit are equally important. A high-performance filter can only provide its intended protection when inhaled air passes through it rather than around it.

For users, the practical message is straightforward. Choosing a respirator involves more than selecting an efficient filter. Achieving and maintaining a close fit is just as important.

What Should Readers Do With This Information?

• When choosing any respirator—not just Totobobo—consider the following questions:
• Has the filter been independently tested?
• Is there independent evidence supporting the manufacturer’s claims?
• Can the respirator be adjusted to fit your own face properly?
• Can you identify and correct obvious gaps before use?
• Is it comfortable enough that you are likely to wear it consistently for as long as protection is needed?

The available evidence suggests that Totobobo performs well against these criteria when properly fitted. More importantly, these same questions provide a practical framework for evaluating any respirator.

—

Frequently Asked Questions

Does a higher filtration efficiency always mean better protection?

Not necessarily. Filter efficiency measures how well the filter material removes particles under test conditions. Actual protection also depends on how well the respirator fits the wearer and whether inhaled air bypasses the filter through gaps.

Why is the Totobobo mask transparent?

The transparent body was designed to make the fitting process easier to observe. Users can visually inspect how the mask contacts the face and identify obvious gaps that may require adjustment. Although this does not replace quantitative fit testing, it provides practical visual feedback that opaque respirators cannot.

Can visual inspection replace a PortaCount fit test?

No. Quantitative fit testing remains the recognised method for objectively measuring respirator fit. Visual inspection is intended only to help users improve the fitting process where professional testing is unavailable.

Why does this page include studies that were less favourable to Totobobo?

Because scientific evidence should be presented in context. Earlier studies identified limitations in prior designs, leading to subsequent improvements. Including both favourable and less favourable findings provides a more complete and transparent picture of the development and available evidence.

Does this article prove that Totobobo is the best respirator?

No. The studies reviewed here evaluate specific aspects of Totobobo’s performance. They do not compare every respirator on the market or support claims that one respirator is universally best for every user or every application.

—

References

Supporting Large-Scale Research

• Tongji University. Fitting Characteristics of N95 Filtering Facepiece Respirators Used Widely in China. (2014)

Independent Laboratory Testing

• Nelson Laboratories. Particle Filtration Efficiency Report. ASTM F2299. Totobobo F96 Filter. (2014).

University Research

• Liu NM, Wan T, Russell-Jones EC, Grigg J. Can Masks Protect You From Air Pollution? Thorax. British Thoracic Society Winter Meeting. (2017).

Hospital Studies

• Au SSW, Gomersall CD, Leung P, Li PTY. A Randomised Controlled Pilot Study to Compare Filtration Factor of a Novel Non-fit-tested (HEPA) Filtering Facemask with a Fit-tested N95 Mask. Journal of Hospital Infection. (2010).

• Hui CYT, Leung CCH, Gomersall CD. Performance of a Novel Non-fit-tested HEPA Filtering Facemask.(2017)
• Li et al. The Effect of Ethanol Immersion on Fit Performance and Comfort of a Fit-tested Reusable Mask. Journal of Industrial Textiles. (2022).

—

Editorial Note: This article summarises published laboratory reports, university research and hospital studies relating to Totobobo and respirator performance. The findings are presented as accurately and objectively as possible. Where studies have limitations or report less favourable results, they are included alongside later research to provide a balanced overview. As new evidence becomes available, this article should be updated accordingly.

2026-06-28 Last reviewed by Francis Chu, Inventor, Totobobo mask

As featured in: Associated Press