Smart Air QT3 Review – Are Portable Air Purifiers Worth it?

Over the past few years, people have begun looking for additional measures they can take to protect themselves beyond wearing a respirator. This has caused a few new product categories to become quite popular, one of which is far-UVC lighting and another of which is portable air purifiers. Today, I finally have a chance to try my first device in the latter category – the Smart Air QT3 portable air purifier.

This small device is aptly named as it’s a cute device that, while not exactly small, is vastly smaller than what comes to mind when I hear the term ‘air purifier’. Of course, this small size, combined with the fact that the device is battery-powered, leads many to ask how effective such a small device can actually be. While it’s well known that reputable larger air purifiers are capable devices, does this also carry over to this new niche of smaller, portable devices? In my review today, I aim to answer this question.

If you are already aware of Smart Air, you will likely already have some idea of what to expect with this device. However, for a long time, they were one of the only companies to produce simple but low-cost air purifiers that prioritise performance over design and features. While they still follow this philosophy, a few other companies now exist in this space (like AirFanta and Nukit). With that said, Smart Air has created a good reputation for itself with minimalist yet performant air purifiers, and I’m excited to try this device!

Before even discussing the QT3 in detail, it’s important to note that this device is not intended to be used as a traditional air purifier. That is to say, you can’t leave it in a room and expect it to clean the air in the room (well… You could, but it would take a very, very long time). Rather, this device is intended to be a ‘personal’ air purifier that can be placed near a person to provide them with a stream of clean air. This does have limited effectiveness, but there are also use cases where it’s useful, and we will discuss those soon. For now, it’s just important to know that this shouldn’t be used like a traditional air purifier, and if that’s what you’re after, you will want to look elsewhere.

With that quick disclaimer out of the way, we can jump into this review! If you’ve already tried the QT3, I would love to hear your thoughts. Please feel free to comment at the end of this post if you have something to share or if you have any questions remaining after reading the article. Let’s get started!

This post contains affiliate links. For more information, please refer to my affiliate disclaimer. I was sent a product for review, but the article is not sponsored. All opinions expressed in this post are my honest thoughts. I only recommend products that I genuinely believe in.

Information on this blog is for informational purposes only. Readers are encouraged to confirm the information herein with other sources. Furthermore, this information is not intended to replace medical advice from professionals. This website assumes no responsibility for the accuracy of the information, and information is subject to change without notice. Devices mentioned on this website are not medical devices and do not guarantee protection.

In The Box & Variants

The Smart Air QT3 is available in two different configurations – Travel and Home. The only difference between these two devices is that the Travel variant comes with an internal battery, whereas the Home model does not include this. I’m not sure what the intention of the QT3 Home is, but it could be a good choice if you want a device to keep on your desk at home or in the office. Since the device is intended to provide a stream of clean air (we will discuss that in more detail soon), I wouldn’t recommend it for other uses.

The Travel variant, on the other hand, is a much more interesting and useful product. This device comes with an internal battery and is only slightly more expensive, so I feel like the choice between these two is a no-brainer. While Smart Air is very clear about which device you are purchasing, you will want to ensure you are buying the Travel QT3 if you purchase from another reseller or distributor.

In the box, you will find the QT3 itself, a mesh carry bag (if you’ve purchased the Travel purifier), a manual, and a USB Type A to Type C cable (the QT3 uses Type C). As with many products, there is no USB adapter included, but this shouldn’t be an issue for most users as most of us already have a few lying around the house. The mesh bag is also a nice inclusion, making the QT3 a bit more carry-friendly.

Performance

The question that is highest on most people’s minds when it comes to a product like this is ‘Does it actually perform?’. Well, that was the first question on my mind, at least! At the end of the day, a product like this is useless unless it’s performant, so let’s first look at how well the Smart Air QT3 filters and what you can expect from it regarding performance.

The QT3 has a CADR (Clean Air Delivery Rate) of 37m³/h, meaning you can expect it to clean that air volume in an hour. Of course, this is at the highest fan speed (speed 3), and the other two speeds will have significantly lower CADRs than this. Now, at first glance, this seems like quite a poor number, as many other purifiers have many times that. However, it’s important to mention that this device is intended to be a ‘personal air purifier’. In other words, it’s designed to be placed in front of the user and provide a column of clean air instead of purifying an entire room, as with most purifiers.

The QT3 uses a HEPA H11 filter designed to filter ≥ 95% of particles at 0.3 microns. Of course, this means it will filter both larger and smaller particles at a higher efficacy due to the physics of fine and ultra-fine particle filtration and the most penetrating particle size (MPPS) phenomenon. It’s also worth noting that since the device does not have an activated carbon filter, it will not filter VOCs or nuisance odours. While this is expected for a device of this size, some people may be disappointed at the lack of a carbon filter. Personally, I am not too fussed by this exclusion on portable air purifiers as, even on larger purifiers, these filters have limited effectiveness.

With devices like this, it is quite difficult to assess performance as the ‘pillar’ of clean air in front of the device tends to be quite narrow and mixes quickly. Furthermore, the types of devices that measure the performance of something like this with high accuracy are very expensive. That said, I have a range of consumer-grade air quality monitors, and I wanted to do some of my own testing. However, before getting to this, I was interested in seeing what Smart Air themselves have to say.

Below is a graph that shows QT3 performance based on Smart Air’s test (although they revised this test a couple of months ago, and we will discuss this second set of results in a minute). As you can see, as per Smart Air’s results, the QT3 will provide between 98% filtration and 20%, depending on the distance in front of the device. This is all at the device’s max fan speed, and we can expect less performance at lower speeds.

Realistically, in most situations, you will probably have the device a minimum of 30cm from your face, and I found I usually had the purifier 30-70cm away from my face. In this range, I should be experiencing around a 50% to 35% reduction in particles, depending on how far away the device is placed. While this may seem quite low, it’s worth noting that this device should only be used as a layer in your personal protection steps.

Let’s use a (very simple and imperfect) example. Let’s say you’re wearing an N95 respirator, which provides a minimum of 95% filtration when fitted correctly. If there are 100,000 particles in the air, up to 5000 could still pass through the respirator filter. However, if we first reduce that to 50,000 particles with a device like the QT3, we are now only breathing 2500 particles. This is a very rough and imperfect example, but I want to convey here that a device like this should merely be a layer in your protective steps rather than the one device you rely on. In this case, it can be quite useful!

Most people will probably purchase this device to help filter airborne viruses. However, in a situation where you’re using this to filter less dangerous particles (especially in low concentrations), the QT3 can also be a helpful tool. I’m currently in New Zealand, and while the air quality is very good generally, I sometimes see the AirGradient ONE on my workdesk show 3ug/m3 of PM2.5 – with the QT3 blowing in my face, I can reduce this number to one or zero. In this case, the QT3 is also quite handy.

Moving on, Smart Air ran this test again on the floor (to minimise airflow interference from other sources) and got the above results at a distance of 30cm. While it’s hard to tell which test is a better indication of overall performance, what I take from this test is that at high, the device has about 25% better filtration efficacy than at low speed. Low to mid also shows a 15% increase. These numbers show a far lower change than I would have expected, and I’m curious if the difference is more obvious at further distances from the QT3.

Of course, I was interested in seeing if I could verify these numbers. While Smart Air is definitely on the more transparent side of companies, I can’t provide a review without at least some of my own testing! Therefore, I devised a setup that, while far from perfect, at least gave me some insight into how this device performs. Now, I must state that this is far from scientific, and I’m sure my experiment had some flaws. However, it is the best I can do without a lab and thousands of dollars of equipment.

Firstly, I got five air quality sensors. Since I didn’t want to encounter variability due to different sensor types, I opted for five of the same monitors – in this case, I used five AirGradient monitors. I placed the QT3 on a desk and measured 30cm, 50cm and 1m distances directly in front of the device. For the first experiment, I placed one monitor 10cm behind the QT3 (to measure the air quality of air going into the device), one monitor directly in front of the device (first 30cm in front, then 50cm, then 1m but not at the same time), two monitors 30cm to the left and right of this monitor (to see how wide of an area the QT3 purifies) and one monitor elsewhere in the room to be used as an ambient concentration monitor.

I then closed all the windows and doors in the room and ensured there was no other active airflow from devices such as fans, air conditioning, HVAC systems, etc. In other words, I ensured the air in the room was as still as I had control over. Finally, I lit a stick of incense in the room and left it to burn down, bringing the room to a rather extreme but quite consistent 1500µg/m3 of PM2.5. I then let the QT3 run at different speeds with the air quality monitors at different distances from the front of the QT3 to see the results. I ran each test for around 20-25 minutes.

Above are my first results, testing the QT3 at the third (and fastest) fan speed with a monitor 30cm directly in front of the purifier. As you can see, the monitor 30cm in front of the QT3 recorded just under a 50% reduction in particles (on average) over the 20-minute period. This result is quite similar to (but slightly lower than) the first set of results that Smart Air published but is significantly lower than the second set, which mentioned a 75% reduction at 30cm. I ran this test several times after this experiment to confirm my findings, and my best result was a 53% reduction over a five-minute test. Overall, I would say that at 30cm with the device at maximum speed, we can see a 45-55% reduction in particles.

The second test (shown above) was recorded when I moved the air quality monitor in front of the QT3 from 30cm to 50cm. As you can see, having the QT3 an extra 20cm away significantly drops the air filtering capabilities. Here, we see a 30-35% decrease in particle concentration compared to the previous 45-55%. Again, this is quite similar to the initial Smart Air findings but slightly lower.

I repeated this test once more with the air quality monitor sitting one metre in front of the QT3. This is probably what I would consider to be the maximum ‘useable’ distance for this device, and you can see it only results in a 15-20% reduction in particle concentration. With that said, in the confined spaces this device is designed for, one metre is quite a long way, and I wouldn’t expect it to be often used at this distance.

Of course, all of these tests were carried out at the third and fastest fan speed. While I didn’t have time to run through tests combining every different distance and fan speed, I also wanted to test the slowest fan speed at 30cm. In this case, I found the device to provide somewhere between a 30-35% reduction in particles compared to 45-55% at speed 3. Again, this is similar but more conservative than Smart Air’s results, which show a 25% reduction in performance at speed 1 vs speed 3. While I don’t have the graphs to show, when I ran a few shorter tests, I found speed 2 to provide around a 15% reduction compared to speed 3 – again, a similar result.

To be frank, I’m quite surprised by this result. The audible difference between the three fan speeds is significant, and I would have thought that the first speed would have provided a much more significant decrease in filtration performance than the fastest speed. However, this result pleasantly surprised me, and I think the lowest fan speed may have some usefulness in certain circumstances.

Earlier, I mentioned that I also had two more monitors set up, 30cm to the left and right of Monitor 1 (which was directly in front of the QT3), to measure how wide the column of clean air from this device is. Below is a graph that shows the average reading of these two monitors, which were located 42cm from the QT3 on something close to a 60° angle. The green line shows the particle concentration directly in front of the QT3, the purple on the two sides, and the red unfiltered air. As you can see, while the centre monitor gets the largest reduction in particle concentration, the QT3 also provides cleaner air if you’re in front of it but at an angle – at least, as long as you’re very close to the device.

These results indicate that Smart Air has shown is pretty much true. The QT3 can significantly reduce particles directly in front of the device, and this can make it a good layer to add to your protection strategy. However, for the best results, you should be as close to the device as possible to the QT3 (ideally around 30cm away from it), and it should be at the maximum fan speed. While the lower fan speeds still provide decent filtration at 30cm, they significantly drop off at longer distances (although, to be fair, so does the fastest speed). Furthermore, the QT3 is definitely intended as a portable *personal* air purifier, as the column of clean air is not wide enough to provide significant protection to someone else, even if they’re sitting in a plane seat or at a table next to you.

I haven’t yet tested the QT3 compared to other portable air purifiers, but I am happy that this type of technology works. I’ve had doubts about these portable devices in the past, and it’s good to see that at least some perform as claimed!

Before concluding this section, I want to note that I didn’t test this device like a typical air purifier (measuring the reduction in particles in a room), as it’s clearly not intended for these use cases. It’s obvious upon seeing the device that it’s underpowered for even a small room, which makes sense considering its portable design. Instead, I opted to measure the particle count directly in front of the device, as the QT3 is intended to be aimed directly at the user. If you are interested in how this device performs in a car, HouseFresh investigated this in their review, and I highly recommend checking it out!

Design

Smart Air has always prioritised function over form, which allows it to maintain affordable prices across its range of air purifiers. I mention this priority because it is reflected in the design of not just the QT3 but all products in the Smart Air range. This isn’t to say the QT3 isn’t well designed (in fact, it’s my favourite compact air purifier in terms of aesthetics), but this is a simple device designed for function first.

The Smart Air QT3 is small and portable for an air purifier at 1.375 pounds (0.624 kgs) and 150 x 145 x 180mm. If you’re measuring that in your head as you read it (or with your fingers, as I often do), you’ll quickly realise it’s a very compact device but not exactly one that will fit in your backpack. On the other hand, if you are travelling with larger hand luggage (such as a 55cm tall suitcase which I often use), this device will easily fit inside. Since it’s lightweight, it also won’t take up much of your carry-on weight!

That said, this device isn’t the most convenient to transport. I’ve found cylindrical portable air purifiers such as the Airinum Hale to be more convenient to carry as they can easily slide into my backpack. However, I can’t recommend these devices as I haven’t yet reviewed them – I just find them more portable due to the more convenient form factor. It’s also worth noting that the QT3 is a bit heavier than some of these other devices, and while I don’t find this to be a big inconvenience, this may be more important to you.

Onto the design itself! The QT3 is an almost fully plastic device with a handle that feels like faux leather. While the build quality generally feels good enough – especially at this price point! – I have been told by many of my followers on X/Twitter that the handle can quite easily break at the mounting point, leading many users to make DIY improvements. While this issue will likely not impact most users unless their device is suddenly jerked, I must admit that the strap does not feel entirely trustworthy.

Luckily, my impressions of the build quality changed after moving past the handle. While the rest of the device is plastic, the quality feels decent, and I’m not worried about any part of the device breaking. Fortunately, the device also doesn’t feel like it needs to be ‘babied’, and during my first car trip with the device, it held up well despite being stored in the boot for a while, along with larger bags and falling a couple of times due to sudden stops.

Looking more closely at the device, the front is dominated by ten louvres with an adjustment tab that allows the user to angle the direction of the airflow. I would estimate that the airflow angle can be aimed at about 30° up to almost directly down, although you wouldn’t want to use either of these extremes in any situation I can think of. Unfortunately, there is no horizontal adjustment, meaning the device will need to face you directly whenever you use it. However, although I’m no physics expert, I imagine there would be some issues with allowing horizontal adjustment, and this seems like a very fair design decision.

At the bottom of the louvres, another tab will allow you to pull off the front face of the device, giving you access to the HEPA filter found within. As mentioned, this is an H11 HEPA filter with dimensions of 118 x 112 x 44mm, making it very compact. The filter comes wrapped in plastic, and you will want to remove it before using the device for the first time. One feature that can’t be overstated, which I appreciate greatly, is that each filter is labelled to show which side should be aimed outwards.

The sliding mechanism that the QT3 uses to allow for filter replacements is super easy to use and very convenient. While you shouldn’t need to change filters very often, it’s always nice to know that the process is straightforward. Furthermore, the filter looks to fit quite snugly in the tray, and the only gaps I can see are at the bottom two corners of the filter (as the filter is rounded, but the tray is square). However, these should cause minimal issues if the filter is pushed forward to sit firm against the front of the tray.

Previous models of the QT3 had issues with gaps around the filter once inserted into the purifier. However, this has since been addressed by Smart Air (who, to their credit, listened to the community when they highlighted this issue and quickly resolved it). On my newer model, the only gap I can see is a very narrow slit at the top of the filter. While this doesn’t bother me too much, I tried blocking it with masking tape to see if this is a valid fix, and it worked with no issue. With this change, nearly all air passing through the device should be required to pass through the HEPA filter.

On top of the device are two buttons flanked by four LEDs. These basic status indicator lights will show the current fan speed (levels 1-3), and the fourth will turn on when a filter replacement is needed. Of course, this is only a rough indicator as it’s purely time-based and doesn’t know the air conditions the QT3 has been exposed to, but I appreciate this inclusion as, otherwise, it’s all too easy to forget to change filters.

The buttons alongside these LEDS will allow you to change fan speed (one press to turn on the purifier at speed 1, with the second and third presses increasing speed and the fourth turning the device off) and reset the replacement timer. This latter button can be a bit confusing for new users, and I pressed it many times, wondering what it does as it seemingly does nothing. It wasn’t until I read the manual that I realised it resets the timer for the filter replacement LED and that I should never touch it unless I’ve changed the filter.

Interestingly, there is also a small storage slot at the top of the device that allows the user to store a USB C cable to charge the device. This is handy, but I found that users on X/Twitter had even better suggestions – someone placed an Aranet4 Home in here (it’s the perfect size!), and some people even managed to fit portable batteries in! I thought these uses of this small storage slot were particularly cool, and while I was confused about the slot at first, I now love the inclusion.

Turning the device around further, we have a USB Type C port at the back of the device for charging. This common connection will allow you to charge the QT3 from most other large devices like laptops and PCs while also allowing you to easily charge the device with a USB socket adapter. Since the battery is around 2000 mAh, it will take around three hours to charge if using a capable USB adapter.

Below the USB port is a large inlet behind which the fan lies. As far as I can tell, this is a standard PC fan and could likely be easily replaced with third-party parts if needed. I have heard from a few users on X/Twitter that it’s very easy to break this fan on accident if something is accidentally pushed through the vent (this can happen quite easily if you drop the device, for example). It would be nice to have some finer mesh covering the back of the device, but, unfortunately, sometimes accidents are bound to happen. Luckily, the fan is quite easy to replace, even if you do it yourself.

Finally, you will find four feet at the bottom of the Smart Air QT3. These feet give the device a few centimetres of clearance over whatever surface it is placed on and will mean the device disturbs fewer grounded particles from whichever surface it is placed on. The feet also have rubber tips, meaning the device has some grip on whatever surface you place it on (this is ideal when using it on a plane’s tray table!).

Sound and Power Draw

As mentioned briefly in the design section above, the QT3 is intended to be used portably, and as such, it includes a built-in 2000mAh battery on the Travel model (this is NOT included on the Home model). This battery lasts between two to four hours, depending on which speed you run the device. At the lowest speed, it will last around four hours; at the middle speed, it will last around three hours; and at maximum speed, you can expect the battery to last around two hours.

The device can be charged with either the included USB C to USB A cable or any other USB C to USB A or USB C to USB C. This makes it very convenient to use, and since it’s a relatively low-power device, USB is more than capable in this case. While no USB adapter is included, you can use any 5-volt adapter (which you will likely already have lying around the house).

The battery can be charged in around three hours when using a capable USB Adapter. While you can, in theory, also charge the device via a laptop or PC USB port, it may take longer in these cases (as many of these have lower amperage). Since 5-volt is very common for USB devices, this also means that any decent portable battery will be able to power this device, making this the most convenient way to keep the QT3 powered during longer trips. With a 10,000mAh battery (which is the most standard size for portable batteries) you can expect to increase battery life of this device to as much as 10 hours.

If you’re planning on using the QT3 plugged-in most of the time, you don’t need to worry about electricity draw or costs as the device draws only around 9 watts at max speed and less at the other two speed levels (about 5 watts when charging while off, 5.7 at the lowest speed, and 6.1 at the second speed). While I wouldn’t recommend this device if you intend to keep it plugged in all the time (there are better devices for that), this low power draw means that the electricity costs of running this device will be minimal.

My only complaint about powering this device is that you never know exactly where you stand regarding the remaining battery life. I wish there were three more LEDs that showed battery life, and I wouldn’t even mind if the fan speed level LEDs were repurposed (as it’s quite easy to tell which fan speed the device is at by the sound alone). While this is far from a deal-breaker, it’s hard to know exactly what the battery status of this device is at any given time.

When it comes to the loudness of the device, Smart Air has provided decibel values for each of the three fan speeds. I also wanted to check the dBA levels, though, and below are my results. For anyone unaware, dBA levels are weighted based on the sensitivity of human hearing as we perceive mid-range frequencies more readily than high or low frequencies. Since the dBA reading is closer to how we hear the device as humans, I wanted to include these results, too.

* Values as provided by Smart Air

I’ve had the Smart Air QT3 on my desk for a few days, and when next to my laptop (which has loud fan noises sometimes), it’s audible at the lowest speed but not distracting. However, the sound is quite noticeable at the second and third speeds, and I can hear it over my laptop fans. Of course, while it’s not very loud compared to larger purifiers, you will need to sit next to this device with it aimed at you for it to be effective, making it seem quite loud at times. However, as per HouseFresh’s review (who’ve tested many more purifiers than me!), it is still one of the quietest devices out there.

While the device is quite audible at its higher speeds on a desk, it’s far less audible when being used on a train, plane, or car. Even if you take the QT3 to a typical cafe or restaurant, background chatter and sounds will drown out most of the fan sounds. Since these are the situations in which this device is clearly intended to be used, I think the sound levels are very reasonable.

Before concluding this section, I want to make one note relating to power draw and sound. For some reason, the fan will speed up slightly when the device is plugged in. Based on noise levels, this increase in sound is about 5%, and while I can’t measure the fan speed, I would guess this means that, when plugged in, the fans spin about 5% faster. This is a small difference, but you will notice it if you have the device running on battery and then plug it in. It’s also worth noting that I observed this 4.5 – 6% volume increase across all three device speeds. This isn’t particularly important, but you may get around 5% better performance (and find it slightly louder) when this device is plugged in.

Pricing & Competition

As with all Smart Air products, the QT3 is designed to be affordable by ensuring the device is performant but doesn’t add any unnecessary bells and whistles. While the price will vary based on region, it retails for around $45 (USD) for the Home version and $48 for the Travel version. As mentioned in the introduction, I don’t see any reason to get the Home version, and with such a small price difference, there’s even less reason.

Some portable air purifiers, such as the PureZone Mini, fall right in this same price range (around $45), while others, like the LG PuriCare Mini, come in at significantly higher prices (around $200, but with more features). Based on what I’ve seen online, at standard pricing, you will be hard-pressed to find a portable air purifier that is more affordable than this. Furthermore, the QT3 looks to perform better in this price range than other personal air purifiers (as per HouseFresh and Smart Air). While I don’t have other portable devices to compare to, the rest of Smart Air’s claims appear to be true, so I would believe the image below. On top of this, HouseFresh also found the QT3 to outperform the PureZone Mini vastly.

Replacement filters come in at $24.99 for two, making them $12.50 each. These are very affordable (although to be fair, they are very small, too), and each is estimated to last 800 hours. This means that each should be ready for about one month of usage – a very reasonable lifespan. Since this is not an air purifier you keep on for many hours every day, unlike static air purifiers, I imagine one filter pack would easily last most users one year. Along with the low electricity consumption, the QT3 is a device with a low ongoing cost.

Unfortunately, as this is my first time testing a portable air purifier, I currently don’t have any points of comparison in regard to performance and can only look at price. However, I can say that this device performs well and is among the cheapest portable air purifiers on the market. Again, it shouldn’t be used like a traditional air purifier, but if what you want is something portable, it’s worth looking at the QT3.

Conclusion

The Smart Air QT3 is an interesting device and one that I’m glad to have finally had the chance to review! While the market for portable air purifiers is still relatively niche, I think the QT3 is a good device that does exactly as it advertises. I’m also impressed by how reasonable Smart Air has been with its testing and claims for this device.

If you’re planning to take the QT3 out and about with you, it’s important to remember that this device should only be a layer in your protection strategy. It’s not a replacement for a well-fitted respirator. With that said, if you keep this in mind, the QT3 can be a great addition, and it can make a meaningful impact on the quality of the air you’re breathing. However, remember that you will want to place it as close to your face as possible for the best performance.

Also, if you’re looking for a purifier for a very small space, such as for a car, you might also be interested in the QT3. However, outside of very small spaces or personal air purification, you will want to look at other devices like the Smart Air Sqair. With that said, as long as you understand what the QT3 is designed for and how to use it within these constraints, it is a good device.

I will continue to use my QT3 over the next few months and will add comments below if I notice anything else come up in regard to longevity or performance. If you’ve used the QT3, I would love to hear your thoughts on the device. Furthermore, if you’re interested in purchasing one but still have some questions about the device, please ask in the comments, and I will do my best to reply! Thank you for reading.

Smart Air QT3 FAQ

Smart Air QT3 Review - Are Portable Air Purifiers Worth it?

The Smart Air QT3 is a portable air purifier designed to give the user an extra level of defense against airborne particles. Read here to see how it performs!

Product Brand: SmartAir

Editor's Rating:
3.5

Pros

• Affordable
• Provides around a 50% reduction in particles at 30cm
• Low ongoing costs
• Portable
• Provides an additional layer of protection

Cons

• Some easily breakable parts (handle and fan blades)
• Provides limited filtration
• Shouldn't be used at more than 1 metre from the user