The air purifier also has secondary pollution

Since the smog at the beginning of the year, many people have bought air purifiers. But how much can it do? On May 26, CCTV’s weekly quality report sent five popular air purifiers in the market to the testing department. It was found that the actual test results of PM2.5 removal rate of three of them were lower than the nominal effect, which sounded the alarm for consumers who were too superstitious about air purification products.

In the investigation, the reporter found that although there are many types of air purifiers and different purification methods, the filter type still has the largest market share. This kind of purifier uses porous filter materials to intercept and collect particles suspended in the air, and plays the role of purifying indoor air.

Generally speaking, the filter screen of the air purifier has three or four layers. The first layer is a prefilter screen, which is mainly used to remove dust and hair with large particles; The second layer is a high-efficiency HEPA filter, which can filter inhalable particles with a diameter of 0.3 μ m ~ 20 μ m, including PM2.5; The third layer is an activated carbon filter screen, which is mainly used to remove odor. “If you can’t clean or replace the filter screen that is full of dust and particles in time, the function of the purifier will decline, and the dust and mold accumulated on the filter screen may also cause secondary pollution in the room.” Song Guangsheng, director of the national indoor vehicle environment and environmental protection product quality supervision and inspection center, pointed out that when using a filter type air purifier, we must pay attention to the service life of the filter screen and filter element.

Now, many air purifiers have warning lights for screen replacement. According to the manual, when the indicator light is on, consumers need to replace the filter screen. If there is no indicator light, it is also necessary to observe and compare the service life in the product manual according to the frequency of use, and do a good job of cleaning and replacement.

Usually, the outermost prefilter screen is dirty. When you turn on the machine, you can clearly see black and gray. At this time, it can be cleaned with a vacuum cleaner. If water washing is allowed, it can also be placed under the faucet to wash away the dirt; The washable deodorizing filter screen can be washed under the faucet as required, and the non washable deodorizing filter screen should be replaced according to the service life of the manual; The formaldehyde removal filter screen must be replaced regularly, especially in newly decorated rooms, preferably once a year; Generally, the service life of HEPA filter is as long as 10 years, but it is better to replace it every 2-5 years. In areas with serious PM2.5 problems, it is better to replace it more frequently; If the indoor air is not particularly dirty, the service life of the activated carbon layer is only about 6 months based on the average use time of 6-8 hours a day, and it is best to replace it every six months.

When buying an air purifier, shop assistants often tell consumers that “the filter can be reused by taking it out to dry directly, which will not cause too much maintenance costs, and is especially economical.” However, Song Guangsheng said that exposure to the sun can not prolong the service life of the product. In order to ensure the purification effect of the air purifier, the filter screen should be replaced regularly.

It needs to be reminded that opening windows often to ensure air circulation is a better way to purify. When the outdoor air pollution is serious or the indoor environment is polluted, the air purifier can be used to play an auxiliary role. When opening the air purifier, close the doors and windows to create a relatively closed environment to ensure better purification effect of the product; If the outdoor air quality is good, it is not necessary to open the air purifier for a long time, and ventilation should be the first choice. The air purifier should not be placed against the wall or furniture as far as possible, and it is best to place it in the middle of the house, or at a distance of more than 1m from the wall when in use. Since there are many harmful gases around the purifier, generally do not put it too close to the human body.

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