The smog comes from the outside. It has three pollutants: respirable particulate matter, sulfur dioxide and nitrogen oxides. Among them, the inhalable particulate matter is larger than PM2.5, which is between PM5 and PM10, because it has relatively large particles, and it can only reach the lower end of the respiratory tract. The human body is generally resistant to its own immunity (of course, the harm caused by severe persistent haze days is another matter). The most harmful to health in the smog are two chemical gaseous pollutants, namely sulfur dioxide and nitrogen oxides. The former is mainly chemical pollution produced by heavy chemicals, and the latter is mainly chemical pollution caused by automobile exhaust.
In order to completely remove the smog, the key is to have a good air purifier. The inhalable particulate matter is removed by the primary filter element and the HEPA filter element. Sulfur dioxide and nitrogen oxides are removed by activated carbon cartridges. Most air purifiers on the market have no problem except for inhalable particulate matter. But the effect on sulfur dioxide and nitrogen oxides is not very good. The main reason is that the weight of the activated carbon filter element is relatively light, the filter element is very thin, and the structure uses a sheet-shaped filter element to match the side-in and out-in and out-out wind structure. The wind distance is short and the polluted air stays in the filter element. The time is short, so the purification effect is not good. These two chemical gaseous pollutions are the most harmful pollutants in the haze. Therefore, many experts pointed out that ordinary purifiers with flake and thin filter elements are very beautiful despite the large air volume and CADR values. In fact, from the perspective of removing smog, from the perspective of ensuring respiratory health and safety, the effect is not satisfactory. Because this ordinary purifier can only maintain indoor "sub-clean environment.