Hazy days, air purifiers are useful?

Haze days coming again, the air purifier is useful or not? How should be used correctly? How should be selected?

　　In April 2015, Tsinghua University released the "Data Analysis Report on Indoor Air Quality Research", saying that modern people spend 80% of their time indoors, and the per capita indoor PM2.5 inhalation is four times that of the outdoors.

　　The correct use of air purifiers is necessary to improve indoor air quality.

How long does a purifier need to be on to work?

　　After the purifier is turned on, there is an indoor air exchange process, which causes the larger pollution particles that originally settled on the ground to rise into the air again. Indoor air pollution will rise instead of fall, and this process will last 20-30 minutes. After that, the pollutant concentration will decrease with the increase of purifier working time.

　　Therefore, we need to pay attention to environmental hygiene, and we should try to keep the environment around the purifier as neat and clean as possible. Zhang Lin, an associate professor from the Department of Electrical Engineering of Tsinghua University, said that the air purifier may produce secondary dust within a short time when it is turned on, so it is recommended that people should not turn on the air purifier for shorter than half an hour.

　　The efficiency of the purifier depends on the amount of clean air (CADR), that is, the amount of "clean air" provided per unit of time. the larger the CADR value, the stronger the purification ability of the purifier. The time required to purify indoor space = (room volume / purifier CADR) x (2 or 3).

Can I open the windows for ventilation when the haze is serious?

　　It is important to find a good balance between opening windows for ventilation and air purification. Even if the outdoor air is bad, indoor places with a lot of people should still choose the opportunity to ventilate.

　　When the outdoor air quality is poor, you can open the windows for a shorter period of time, close them for a longer period of time, and keep the air purifier on all the time. For example, when you get up and leave your bedroom in the morning, you can open the window for a short time to ventilate, and once you return to your bedroom, you can close the window and turn on the purifier immediately.

　　When the outdoor PM2.5 monitoring value is lower than 75 micrograms/m3, which is excellent, opening windows and ventilating is good for indoor air quality, while when the outdoor PM2.5 monitoring value is higher than 150 micrograms/m3, the act of opening windows and ventilating also becomes a destructive factor for indoor air quality.

Where should the purifier be placed?

　　Purifiers should be placed closer to the space where they are located.

　　Experts point out that PM2.5 has a relatively long suspension time, and if people and purifiers are far away from each other, the air quality around the human body will not be improved as soon as possible. It is best to put the purifier next to where the person is, and close the doors of other unused rooms to ensure the cleanliness of the air around oneself.

How often should I change the cartridge of my air purifier?

　　There is no uniform requirement as different types of purifiers and different usage frequencies can affect the cartridge replacement time. Experts suggest that under Beijing's weather conditions, it is best to replace the purifier cartridge once every 1-2 months if it is used at a normal frequency.

Experts give a specific method of judgment: If you take apart and find that the purifier cartridge has turned black, or touch it gently with your hand and you can see the obvious dust coming off, it is time to change the core. If you smell a bad smell and then change it, it is actually too late.

　　Tsinghua University Building Environmental Testing Center Director Zhang Yinping, a more convenient way is to put the home PM2.5 detector on the air purifier outlet, if you find that the number is no longer reduced or the drop is very small, it is the time to replace the cartridge.

How to buy air purifier?

　　Selection is still in pursuit of "purification rate"? Clean air volume, cumulative purification volume has become the "new favorite".

　　According to the new version of the "air purifier" national standard, the clean air volume, the cumulative purification capacity of the two indicators to evaluate the purification capacity to replace the previous "purification rate" indicator. CADR represents the purification capacity of the purifier, the cumulative purification volume (CCM) is the durability of CADR indicators, the greater the level, the longer the life.

　　In addition, the head of the National Standards Committee told reporters that it is best to understand the working principle of purifier products, the evaluation method of purifiers, especially the main technical indicators of air purifiers before purchasing.