Which effect of the measured anti-haze mask is good: cotton is not as good as non-woven fabric

Since this winter, haze has plagued the ancient city from time to time. Recently, Xi'an has once again suspended classes and restricted travel due to heavy pollution. In the murky air on the street, occasionally a few pedestrians who don't wear masks will make people anxious for them. Cotton masks, cotton masks with filter elements, and disposable anti-haze masks are the masks with the highest rate of wearing on the street. They are also the best-selling masks in pharmacies and supermarkets. Compared with last year, there are more 3M masks with breathing valve users this year . But in this year's weather with frequent heavy pollution red warnings, which mask is better for preventing haze? A reporter from China Business Daily and a teacher from Xi'an Jiaotong University will tell you through experiments. Mask anti-haze experiment: -Experiment time: January 3 -Environmental conditions: heavy pollution (PM2.5: 2933.5 pieces/liter; PM5: 474 pieces/liter; PM10: 101 pieces/liter.) -Experiment location: Xi'an Transportation Micro-Nano Center, School of Materials Science and Engineering of the University-Supervisor: Teacher Zhang Pengcheng from the Micro-Nano Center-Experimenter: Cai Yahui, a student of the 2013 Qian Xuesen Experimental Class of Xi'an Jiaotong University-Principle of the experiment: Place a small air pump in a 10-liter volume sealed fresh-keeping box, and Open at the front and rear ends of the crisper. Use tape to seal and fix the experimental mask outside the air inlet. The air pipe of the air pump is connected from the air outlet at the other end of the fresh-keeping box to accelerate the air flow in the fresh-keeping box, so that the air in the fresh-keeping box enters from the mask and is discharged by the air pump, simulating the human breathing process . Place the dust particle counter outdoors for 30 seconds to test the average number of pollutants in the haze weather, then place the counter in the fresh-keeping box, turn on the air pump, cover the fresh-keeping box lid, and place it outdoors In the haze environment, test the number of pollutant particles that enter the'simulated human breathing box' after filtering through the mask. After 15 minutes, the filtration efficiency of each experimental mask for particulate pollutants of various particle sizes was obtained. At the same time, conduct a breathability resistance test for each mask. A total of 8 types of masks were tested this time, all labeled as anti-haze masks, of which 5 were cotton masks and 3 were disposable non-woven masks, with prices ranging from 4.5 yuan to 49 yuan. Shopping locations are pharmacies and large supermarkets. Experimental results show that cotton masks are not as effective as disposable non-woven fabrics in filtering PM2.5. Conclusion analysis: Non-woven masks have good anti-haze effects. Children under 3 years old are not suitable for wearing anti-haze masks. It can be seen from comparative experiments that the filtering effect of cotton masks with filter elements is about 85%, and that of non-woven fabrics is more than 90%. In general, the filtration performance of non-woven masks is better than that of cotton masks with filter elements. This is because the filtering effect of the non-woven fabric is overall, while the cotton mask with the filter element only filters locally. The part around the filter element is cotton, which has a very limited filtering effect on PM2.5. Cai Yahui said that for some cotton masks with filter elements, the precautions in the instructions also reminded that it is recommended that the'filter' be used for no more than 3 days. In addition, because anti-haze masks have barrier properties to PM2.5, the air permeability is not as good as ordinary cotton masks. Therefore, there are instructions to remind children under 3 years of age that their lung capacity is low, and anti-haze masks are not recommended. 'Wear masks and glasses to check the fit through breath. In addition, the fit between the mask and the face also determines the protective effect. From the actual wearing effect, the disposable three-dimensional anti-haze masks on the market and facial stickers Better fit, to avoid unfiltered air entering from the gap. The cotton cloth is not easy to fit tightly with the face because of its good air permeability. Inspectors said that in order to check the fit of the mask, you can wear the mask and glasses at the same time. If the glasses are quickly covered by breath, it means that the mask and the face are not tightly fitted. This is why many people who wear glasses are reluctant to wear masks. This can be avoided if masks are purchased and worn properly.