Roidmi P8S Air Purifier Review: Muscle up on air quality

The Roidmi P8S offers quick air-purifying performance in a high-tech, but wide-shouldered package


Here comes a high-tech air purifier, this time from China. Some might find that ironic, but in Shanghai or Beijing, having an in-car air purifier is a must, at least compared to Singapore.

But it’s not like having one here isn’t useful either: We’ve reported on the fact that Singapore’s air quality is actually rather terrible (‘Why Singapore’s air quality is much worse than you think, 2016) and in-car air quality isn’t a given either (“Is your car killing you slowly?”, 2018).

Even if your car has one of these you still need to mind air pollution

To summarise, the air isn’t as clean as you think, both inside and outside your vehicle, and you should take it seriously because air pollution kills millions globally each year.

The culprits include particulate matter, such as PM2.5 and PM10s – the number refers to the micron-size of the particles, these include soot, smoke, the components of haze and more.

There are also pollutants such as volatile organic compounds (VOCs), oxides of sulphur, oxides of nitrogen, and carbon (carbon monoxide and dioxide). Inside the car, materials used in car construction can give off VOCs, formaldehyde, and more.

The Roidmi P8S

Car air purifiers aren’t a new thing, we’ve tested the Singapore-made Octygen and covered the launch of 3M’s own 3M Vehicle Air Purifier Plus last year.
Roidmi is a new name in the game – the Chinese car accessories maker is part of tech giant Xiaomi – and it’s launched the P8S air-purifier, which is touted as a fast-working in-car air purifier that’ll remove a spectrum of bad stuff from your car’s cabin.

How fast? Roidmi claims the P8S has a clean air delivery rate (CADR) of 70m3/hr, which means the air inside the cabin of an average sized sedan, at three cubic metres, takes around two minutes to be fully refreshed.

Handling the P8S in person, that’s believable as it’s quite a large piece of equipment, at 38cm x 11.8cm x 11.8cm, it’s around the same size as a boxed wine bottle, and definitely not the sort of device you can tuck away under the seats.

Roidmi recommends you install the unit behind a head restraint (aka head rest) and it supplies a mounting bracket and compression straps for that purpose. Two carabiner-style clips lock onto the metal arms of a headrest, while the straps keep the unit tied in place. It works well, though you’ll still hear an occasionally soft ‘thunk’ if you crest a speed hump too quickly.

The P8S has a unique cylindrical design inside, the long filter element (the purple bit) spanning almost the whole length of the unit. Three air intakes, visible as the perforations on the side, feed the air filter, and clean air exits on the two ends.

There’s a monochrome OLED display on the side that shows you the air quality (in PM2.5, detected by an in-unit laser air quality sensor), filter life, and operating mode. You can also pair it to an app via Bluetooth for closer monitoring of operation. During our test drive, the unit showed the PM2.5 level dropping from 10 to 4 within ten minutes.

Filters cost USD20, and should last three to six months, says Roidmi, depending on how dirty the air is. There’s an automatic filter replacement indicator, where the green light turns yellow.

The filter element is the heart of the unit, and it has three layers. The first is the outer pleated layer, which removes all the ‘big stuff like hair and dust, the second is a ‘high-density H11-class filter’ made by Toray Industries. The third is an activated carbon layer – that’s important as filters without activated carbon can’t do anything for chemicals like VOCs and formaldehyde.

RFID is for detecting only genuine air filters, we presume

Operating the unit is simple enough: plug it into a 12V socket and it runs on auto mode. It also has a thoughtful USB pass-through so you can still charge your phone. The single button switches modes (fast, auto, favourite), and the unit is very quiet in operation, so you usually can’t hear it operate above the noise of traffic.

Without ignoring the hypocrisy of running an air purifier in your car while the car itself spews out pollution to everyone around you, we installed the P8S into a test car, the Jaguar I-Pace electric vehicle.  

The Jaguar’s front sport seats have a single-piece backrest, so mounting it in front wasn’t possible, and that meant strapping it to the middle headrest in the second row, which meant it blocked a little of the view out of the rear window.  The I-Pace has a relatively low roofline, and the unit was too long to mount to either side, so this is something owners of coupes and coupe-SUVs should be aware of.

Another issue was that using the hard tonneau cover meant that when opening the boot, the P8S would foul the headrest and tonneau, so we had to go without the latter. In a pinch, we could have simply left the P8S on the boot floor, but that would also mean it moving around during spirited driving.

The I-Pace isn’t a typical car though – in a normal passenger car or SUV, it’s likely none of these issues would occur, but as mentioned, owners of sports or exotic cars where space is at a premium need to plan ahead. Also if you do often carry large items and need to fold the seats down, you need to be careful of the wires and of avoid putting items directly on the purifier itself.

The OLED screen and a real-time readout of the air quality is a nice touch, and shows the Roidmi hard at work. For those in smaller cars, finding a place to mount the unit might be tricky, but overall, the P8S delivered impressive performance in a sleek, high-tech package.

Roidmi P8S USD169
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about the author

Derryn Wong
Has a keen interest in all things mechanical, technological, animal and mineral. Is particularly fascinated by eco-cars and cars which make no logical sense. An avid motorcyclist and photographer, he also enjoys cats.