Xiaomi Mijia Air Purifier 4 Review: 4th Gen Successful Purifier


Xiaomi released the latest Xiaomi Mijia Air Purifier 4. The biggest improvement is the addition of catalytic activated carbon to the filter element. Compared with traditional air purifiers, it has an additional formaldehyde removal function.

Everyone knows that newly-decorated rooms or newly-purchased furniture, because of the release of formaldehyde, often cause the room to be put on hold for several months before moving in. Now the appearance of Xiaomi Mijia Air Purifier 4 has solved this problem to a certain extent.

The Mijia Air Purifier 4 uses an E12 filter element with a filtration efficiency of about 95%. The built-in fan supports 6-speed modes, the maximum air volume is 400m³/h, and the CADR value of particulate matter and pollen is also 400m³/h. Compared with the previous generation, the ability to remove formaldehyde has increased by 2.5 times, and the CADR value of formaldehyde is 150 m³/h.

In the beginning, in addition to the upgrade of the filter element, the Mijia Air Purifier 4 has many upgrades compared to the third generation:

  • 1. An antibacterial and antiviral coating is added to the filter element, which can inactivate some bacteria and viruses.
  • 2. Added negative ion function to make the air fresher. This feature is turned off by default and needs to be turned on using the Mijia app.
  • 3. The top grille is detachable for easy cleaning of the air duct.
  • 4. Compatible with the filter element of the previous generation Mijia Air Purifier 3.

The specific parameters of Mijia Air Purifier 4 are as follows:

Design & Appearance

The Xiaomi Mijia Air Purifier 4 continues the shape design of the previous generation, with pure white tone and simple lines, and has a high degree of recognition. At first glance, it seems to be a Mijia product.

The measurement of the product is 250x250x558mm, the area is about the same as that of a piece of A4 paper, the net weight is about 5kg, and it is convenient to move. The OLED touch screen can display the current working status and the PM2.5 value of the room.

The OLED screen can display the current PM2.5 value, temperature, humidity, Wi-Fi connection status, and fan running gear. The two main control buttons below are the power-on button and the fan gear adjustment button. The top is the air outlet, and the covering grid plate has a protective design.

The internal fan can deliver 400 cubic meters of clean air per hour, which means that a 20 square meter room can be exchanged 7 times in one hour. After removing the grid plate, you can see the internal fan, which supports 3 levels of wind adjustment, and the maximum air volume is 400m³/h.

The first-level energy efficiency ratio, standby power consumption is 2W, and energy efficiency ratio is 13m3/(W·h). This means that each kilowatt-hour of electricity can purify 13,000 cubic meters of air, and its maximum purification capacity is 400 cubic meters per hour, so it can be calculated that the maximum power of the whole machine is 31W.

There is a QR code under the energy efficiency ratio logo, which can be controlled by the mobile phone after scanning it with the Mijia APP on the mobile phone. Using the Mijia App, there are more control options, such as “favorite mode” we can set the applicable area of ​​the air purifier by ourselves; when the “child lock” is turned on, the OLED screen will be locked and no operations can be performed; if you feel the purifier If the sound of the sound is noisy, you can turn it off here, and you can also set a timer switch.

The round button on the top of the back can be used to adjust the brightness of the OLED screen, the small black dot next to it is the temperature and humidity sensor, and the bottom fence is the particle sensor. Further down is the cover that can be opened, and inside is the barrel-shaped filter element. When required, the filter element can be removed and replaced.

The filter element grade E12 belongs to the sub-high efficiency grade, with a filtration efficiency of 95%. The biggest difference from previous generations of products is that this filter element is also added with catalytic activated carbon, so it also has a certain ability to remove formaldehyde.

However, it should be noted that if the formaldehyde is removed for a long time, it needs to be taken out once a month to ventilate and dry, otherwise there may be two pollutions after the formaldehyde adsorption is saturated.

In addition to formaldehyde, this filter element also has bacteria and anti-virus double coatings that can inactivate bacteria and viruses and prevent cross-infection. The antiviral rate of the H1N1 virus, the antibacterial rate of Staphylococcus aureus, and the antibacterial rate of Escherichia coli all reached 99.99%. Usually, the replacement time of the filter element is 3 to 6 months.

Purification Ability Experience

The test room has a bookcase that has just been bought, using E0 grade environmental protection panels (the product introduction page says so). We first open all the backstages and cabinet doors of the bookcase, close all doors and windows, and let it sit for 10 hours to fully release the formaldehyde and fill the entire room. Entering the room 10 hours later, the measured HCHO value is 0.062 and the TVOC value is 0.442.

Here to explain, HCHO is formaldehyde, and the occupancy standard is 0.08—the measured value of 0.062 is actually quite high, and the pungent smell can be clearly smelled in the room.

TVOC refers to all indoor organic gaseous substances, benzene, toluene, xylene, etc., and the occupancy standard is 0.6-the measured number is also very close to the critical value.

Turn the fan of the Xiaomi Mijia Air Purifier 4 to the highest position and purify it for 1 hour. The HCHO concentration has dropped to 0.006 mg/m3, and the TVOC concentration has also dropped to 0.052 mg/m3, which is almost 10 times lower. The air is very fresh.

PM2.5 purification test

We ignited 10 mosquito coils at the same time for half an hour, making the bedroom PM2.5 value burst, and the bedroom area was about 15 square meters.

After half an hour, you can see the smoke in the bedroom, and the PM2.5 value displayed on the Mijia air purifier and the Mijia PM2.5 detector are both 600. In fact, the PM2.5 value of the room at this time is far more than 600, just because the instrument can only display 600 at most.

Turn the fan of Xiaomi Mijia Air Purifier 4 to the highest position and start to purify. After 20 minutes, the PM2.5 value had dropped to 458, and the smoke was basically invisible.

After purifying for a full 2 ​​hours, the PM2.5 value was finally controlled below 10, and the purifier automatically entered sleep mode at this time, and the noise was basically zero.

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Let me talk about the author’s experience. In order to solve the problem of the large amount of formaldehyde produced by the newly bought bookcases, the new fan was the first thing that came to mind, because there are few air purifiers that can remove formaldehyde.

Before the arrival of the new fan, the door of the bedroom cannot be closed, and the smell of the room is particularly strong. After installing the new fan, the concentration of formaldehyde has been reduced to about 1/3 of the original, but the irritating gas can still be felt when the door is closed.

After using the Xiaomi Mijia Air Purifier 4, I closed the bedroom door, and there was no smell in the room. Of course, in some cities, opening doors and windows for ventilation can also solve the formaldehyde problem, but opening the windows will cause some dust problems.

According to the data measured by the instrument, when the PM2.5 value of the room far exceeds 600, the Mijia Air Purifier 4 can reduce this number to below 10 within 2 hours, and the PM2.5 value has remained at 2 since then. ~4 looks like.

In addition, after adding catalytic activated carbon, Mijia air purifier 4 also has a certain ability to remove formaldehyde. In the case of new furniture constantly releasing formaldehyde, Mijia air purifier 4 can reduce the formaldehyde concentration (HCHO) to 0.006mg/m3, which is about 15 times lower than the national standard for occupancy.

However, it must be noted that activated carbon is very easy to saturate, so after a period of use (usually about 1 month), the filter element needs to be exposed to the sun and ventilated to relieve it, otherwise, it may become a source of secondary pollution.

As for the power consumption, most of the power consumption of the Xiaomi Mijia Air Purifier 4 comes from that fan. Its full load power is about 27W. It consumes about 19 degrees for a month without shutting down, which is roughly equivalent to a small The power consumption of the fan is comparable.

In terms of use cost, the filter element of Mijia Air Purifier 4 needs to be replaced every 3 to 6 months, and the price of the aldehyde removal filter element is 309 yuan 2. If it is replaced every 5 months, the daily use cost is exactly 1 yuan. It shouldn’t be too expensive to buy fresh air for 1 yuan.


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