It depends on what kind of mask you are wearing. When purchasing an anti-smog mask, you can first look at the standard, and secondly, you can look at the filtration efficiency. To talk about the standard, the most familiar ones should be the N90 and N95 series of the 3X brand. Masks are named after NIOSH standards. In addition to NIOSH standards, there are also common ASTM standards of the American Society for Testing and Materials, China's KN standards and European FFP standards, which can all be used to measure important indicators of masks. Ordinary medical masks are relatively cheap and have poor protective properties. They are basically just It is suitable for ordinary nurses or cooking at home; while high-end medical masks are used by surgeons or dentists. These doctors have higher incomes and do not care about the low cost of the mask, but pay more attention to the quality of the mask. High-grade medical masks have excellent barrier properties against particles and fluids, ensuring breathability in precise working environments. It can also prevent odor. The source of toxic particulate matter in the city: firstly, car exhaust. The medical mask imported from the United States has good filtration performance and prevents not only particulate matter but also droplets. The filtration efficiency for particles as small as 0.1 microns reaches 99.8, and the filtration efficiency for bacteria or viral vectors (common in droplets) as small as 0.3 microns reaches 99.9. Using SecureFit patented technology, it can be adjusted to adapt to different face shapes to achieve a high fit. For the health of you and your family, wear a mask when going out. I wish you happiness and hope you will adopt it in J's good style.