Winter is a season with frequent smog weather, and the health hazards caused by smog have become the focus of attention. At the same time, most people spend more than 90% of their time indoors in winter, and the impact of indoor air quality on human health can not be ignored.

Facing the dual indoor and outdoor air pollution, more and more families choose to use air purifiers. For a wide variety of air purifiers on the market, teach you how to choose and use them correctly.

1、 Preparation before purchase

When choosing an air purifier, families should first consider the following three issues: the first is the target pollutants, the second is the place where the purifier is used in the family, and the third is whether there are sensitive personnel in the family.

Step 1: specify the target pollutants to be purified. Indoor air pollutants are divided into outdoor sources and indoor sources. Outdoor sources refer to outdoor air entering the room through air conditioning and ventilation system, natural ventilation, enclosure gap penetration and personnel carrying. Indoor sources include exhaled air discharged from the human body, cooking oil fume, indoor building decoration materials, indoor fungi, dust mites Electromagnetic or static electricity generated by household appliances. For different pollutants, the purification principle of air purifier is different. Therefore, it is necessary to clarify the purification of pollen, dust and PM2 5. Particulate pollutants such as smoke? Or formaldehyde, benzene, volatile organic compounds and other chemical pollutants? Or biological pollutants such as bacteria, viruses, molds and dust mites?

Step 2: identify the main places where the air purifier is used in the family. The purification effect of air purifier is closely related to room area, power of purifier, purification efficiency and other parameters. In addition to the above indicators, noise should also be considered. If it is placed in a large area such as the living room, the purifier with high purification capacity can be selected, and the noise is not taken as the main parameter; If it is placed in the bedroom, the noise should not be too high.

Step 3: we should pay attention to whether there are infants, asthma patients and other sensitive people at home. If yes, it is recommended to buy a pure physical filter air purifier that does not produce ozone.

2、 Purification principle of common air purifiers

Purification principle is an important factor that should be considered when purchasing air purifiers. At present, commonly used purification technologies include the following categories:

• 1. Physical adsorption: represented by filtration technologies such as porous and large surface area materials such as activated carbon and high efficiency filter (HEPA), the combination of adsorbent and adsorbent depends on van der Waals force to purify the air. It is the safest and most efficient filtration method at present. Since all adsorbents have a certain adsorption capacity and weak binding force, desorption will occur when the adsorbent reaches the saturated state, releasing formaldehyde or particles, resulting in secondary pollution. Therefore, it should be replaced regularly during use.
• 2. Photocatalysis technology: represented by photocatalyst and cold catalyst technology, it can decompose harmful gases while purifying. The working principle of this kind of purifier is to coat the catalyst on the carrier and irradiate the catalyst with a specific wavelength of ultraviolet light source. Turn on the fan to make the air pass through the carrier at a certain flow rate, and the catalyst reacts with formaldehyde in the air under the irradiation of ultraviolet light, so as to achieve the purpose of purification. There are many kinds of materials for photocatalysis, such as nano-TiO2, MnO2, etc., and the main product is CO2. The principle of photocatalysis has the characteristics of no secondary pollution, which is in line with the concept of green environmental protection in the new era. The efficiency of purifying formaldehyde is related to many factors, such as the initial concentration of pollutants, indoor temperature and humidity. The blockage of the microporous surface of the catalyst will greatly reduce its purification efficiency.
• 3. Ion technology: represented by negative ion and silver ion technology, it can sterilize and effectively purify the air. Negative ions are the general name of negatively charged ions in the air. They are colorless, tasteless and have strong adsorption characteristics. They can adsorb particulate matter in the air nearby. The negative oxygen ion air purifier generates a strong electric field to diffuse to the air and actively capture pollutants in the air, such as formaldehyde, benzene, toluene, ammonia and other substances, so as to condense and settle them, so as to purify the air. However, strong electric field and discharge process are easy to produce ozone, which is harmful to human body.
• 4. Electrostatic dust collection: it mainly adopts the way of electronic dust collection, uses static electricity to charge particles in the air, and then catches charged particles through the dust collection device, so as to achieve the purpose of purification. It has high dust removal efficiency and can capture 0.01 ~ 0.1um particles. The disadvantage is that the high-voltage power supply is required, the dust collection capacity of the dust collection device is small, and the purification effect is not very ideal. Generally, the dust collection device needs to be cleaned once every 1 ~ 2 weeks. It will produce ozone and bring secondary pollution.
• 5. Biological enzyme purification: Based on the principle of biological decomposition, biological enzyme is a protein with catalytic function, which decomposes the formaldehyde pollutants in decoration materials into water and carbon dioxide, and removes the formaldehyde pollutants at the source without secondary pollution. Enzyme catalysis has the characteristics of high efficiency, specificity and mild action conditions, and can continue to work by using the reproductive ability of microorganisms. There are also some deficiencies in the removal of formaldehyde by biological enzymes, such as the need for appropriate temperature and humidity. If the temperature is too high or too low, the enzyme activity will be reduced or even completely inactivated.
• When purchasing, physical filtration and adsorption technology should be the first choice, and air purifiers with various purification technologies should be selected as far as possible. Air purifiers that produce ozone should be avoided as far as possible.

3、 Selection of air purifier

A truly effective air purifier should achieve "three high and one low", that is, high clean air volume, high cumulative purification capacity, high energy efficiency value and low noise.

High clean air volume (Cadr): clean air volume is a parameter of the purification capacity of the purifier for target pollutants (particulate matter or gaseous pollutants). The greater this value is, the stronger the purification capacity of the purifier per unit time and the better the purification efficiency. The applicable area of the purifier can be estimated by the clean air volume of particulate matter: S = (0.07 ~ 0.12) Q, where s represents the applicable area (unit: m2) and Q represents the clean air volume of particulate matter (unit: m3 / h). For example, the clean air volume marked on an air purifier is 400m3 / h, and the applicable area is about 28 ~ 48㎡.

High cumulative purification volume (CCM): the cumulative purification volume refers to the total mass of target pollutants accumulated for purification treatment when the clean air volume of the air purifier attenuates to 50% of the initial value. The higher this parameter is, the higher the purification capacity is