How big is the influence of smog weather on respiratory diseases?

The main component of smog is PM2.5. We all know that the particle size of PM2.5 is very small and it is easy to enter the lungs through the respiratory tract. It is the carrier of many toxic and harmful gases, carrying a lot of heavy metals and carcinogens, especially carcinogens. Moreover, PM2.5 can be permanently suspended in the air, so smog is very harmful to the respiratory tract. If the smog is serious, it will cause or aggravate respiratory diseases such as asthma, bronchitis and cough. However, it should be noted that PM2.5 is difficult to be removed by ordinary filters due to its small particle size. It is best to use a professional negative ion air purifier with national patented technology, such as VIIYI Wei Yi, and the air purifier that removes PM2.5 has a good effect.