Why do five-star hotels choose in addition to formaldehyde's "blue breath" before opening?

"Blue Breathing" is a kind of photocatalyst technology, which decomposes formaldehyde under the condition of light by spraying and covering. The effect is quite good, but the indoor environment is generally short of sunshine, which has little effect on places without lighting conditions. If you choose to control formaldehyde, you should choose active products, because formaldehyde is attached to the adhesive in the board, and because it is volatile, it will gradually spread into the air to harm people. You have to go deep into the body to take it out.