1, newly renovated house. I believe that many friends who have just renovated their houses know that they can't live in the room immediately after the renovation, because the formaldehyde pollution inside is very serious. In most cases, it takes a month to move in. In fact, you can use an air purifier at this time, which is very useful.

2. Office or public place. These places are also suitable for installing air purifiers because of the large flow of people and serious air pollution such as smoking.