Is the hotel air purifier useful?

Different brands of air purifiers have different effects, but it is certain that they can remove particulate matter, but the scope and efficiency of removal are different. The best way to judge is to know the filter level (the higher the filter level, the higher the filtration efficiency. At present, the HEPA filter used to remove PM2.5 is generally H 13), and the manufacturer is required to give the test report of this type of machine (the report must be complete, not just one page); Test by lighting a cigarette (detector can be selected). Generally, when a cigarette comes down, PM2.5 can produce a chart (500) to test how long it takes for the purifier to reach a safe value.