How to choose the best mask in winter
Sihaiwang: it's winter, and the haze army has quietly sounded the rally. In recent years, the haze in China has become more and more intense, which has gradually attracted the public's attention. The harm of haze is well known and no need to elaborate. The PM2.5 index is the most important indicator to measure air pollution. Many families pay attention to health, and install air purifiers early. As our last defense line, can you really hold on to the masks? The masks in the market are all protected against haze Which kind of mask can be drunk? We choose several mainstream masks to test one by one!
Experimental materials and principles:
One PM2.5 detector, one filter efficiency detector and six anti haze masks
Experimental principle:
After power on, when the fan rotates, it will drive the gas to flow downward, and put the mask on the air inlet. Under the action of the fan, the gas will enter the measuring chamber through the mask from the air inlet. The PM2.5 concentration before power on and the PM2.5 concentration after filter of the mask will be measured respectively.
Using the formula: filtration efficiency = (PM2.5 value before filtration - PM2.5 value after filtration) / PM2.5 value before filtration, the filtration efficiency of outlet hood to PM2.5 can be calculated.
Experimental method:
In a closed room of about 30 square meters, ignite cigarettes to simulate PM2.5 high concentration environment. The original value of indoor PM2.5 is 50 & mu; g / m3. Ignite a cigarette, and the indoor PM2.5 value rises to 151 & mu; g / m3. Cover the six masks with rubber band to the fan port in turn, and observe the change of PM2.5 value 30 seconds later.
1 3M mask (with breathing valve)
The concentration of PM2.5 decreased from 154 & mu; g / M & sup3; to 10.8 & mu; g / M & sup3;
2 3M mask (without breathing valve)
The concentration of PM2.5 decreased from 154 & mu; g / M & sup3; to 5.4 & mu; g / M & sup3;
3 cotton mask with filter screen
The concentration of PM2.5 decreased from 150 & mu; g / M & sup3; to 76.3 & mu; g / M & sup3;
4 thin disposable mask
The concentration of PM2.5 decreased from 149 & mu; g / M & sup3; to 133 & mu; g / M & sup3;
5 disposable medical care mask
The concentration of PM2.5 decreased from 152 & mu; g / M & sup3; to 80.4 & mu; g / M & sup3;
6 general cotton mask
The concentration of PM2.5 decreased from 156 & mu; g / M & sup3; to 129 & mu; g / M & sup3;
Conclusion:
Through experiments, we found that:
The filtration effect of 3M mask without breathing valve is the best, and the filtration rate of PM2.5 can reach 96.5%;
Among the general masks, the most obvious filtering effect is disposable medical nursing mask, the filtering effect is 47.1%;
However, the filter effect of the most commonly used cotton mask is only 17.3%.
Note: this experiment only tested the filtering effect of the filter material in the mask on PM2.5. In daily use, the fitting degree between the mask and the face, and the air tightness of the mask air valve when it inhales, will affect the anti haze effect of the mask.
There is a big difference in the price of masks. There are dozens of yuan per piece and several yuan per package. Most of the sellers mark that they can prevent haze. Among the haze mask products, some of the low and medium price products with a price of more than 10 yuan are especially popular. However, according to the experiment, there are few effective haze masks.
Recommendation:
In addition to the filtering effect of materials on PM2.5, there are two key factors for haze mask. One is whether the mask is close to the face, whether there is much air leakage around the nose and chin, and whether the mask with poor face sealing is equal to not wearing. Here, we tend to recommend the mask on the head instead of the mask hanging on the ear.
Second, whether the breathing is smooth, that is, whether the normal breathing can be guaranteed. If the breath is not smooth, there will be a lot of water vapor. The students with glasses have such experience. After wearing the mask, they will cover their glasses with a layer of fog. Therefore, it is recommended that you choose masks with breathing valves.
In addition, the outer layer of the mask often accumulates a lot of dust, bacteria and other pollutants in the outside air, while the inner layer blocks the exhaled bacteria and saliva. Therefore, the two sides can not be used alternately, otherwise, the dirt from the outer layer will be inhaled into the human body when it directly clings to the face, and become the source of infection. When the mask is not worn, it should be folded and put into a clean sealed bag, and the side close to the nose and mouth should be folded inward. Do not put it into the pocket or hang it on the neck.