Respiratory Protection Guide - Responding to Pollution, Choose Face Masks

First, the birth history of masks

In 1861 , Pasteur discovered the presence of bacteria in the air, which in turn may cause surgical wound infection.

At the end of the 19th century, doctors and nurses began to use gauze to cover their nose and mouth. Since then, the prototype of the mask has undergone several improvements and gradually become the current appearance. Therefore, the original intention of inventing a mask was not to use as a mask.

In 1918 , when the Spanish flu raged, masks came out of the hospital and became the public's standing goods.

At first, people used masks made of multi-layered degreased gauze. Gauze masks are thick and absorbent, reusable, easy to wash, and inexpensive.

Experiments have shown that gauze masks with a sufficient number of layers can filter out a considerable portion of dust and bacteria and have long been the type of mask most people use. However, as people's dust-proof requirements increase, gauze masks have gradually become difficult to meet requirements. The harms of inhalable particles and fine particles in urban air have increasingly attracted the attention of the general public, and gauze masks have less than a 30% filtration rate for particulate matter . In the context of environmental reforms that are difficult to complete overnight, finding a reliable mask to filter out bad air has become the most practical and simple form of personal protection .

The surgeon's surgical disposable mask is an industry-standard medical device. It is divided into three layers, the outer layer has anti-embossing design, the middle filter, the inner layer absorbs moisture, and the mask is made of non-woven material. This kind of mask is mainly used to protect doctors from splashes and splashes. Its particle filtration rate is only greater than 30% , and the filtration rate of bacteria can reach 95% or more. The most important thing is that the edge of this type of mask is not suitable for face design, and in most cases it can only play a role in shielding. This kind of mask is obviously also not suitable for blocking particles in the air.

Although the cartoon mask is cute, but the protective function is not strong

Second, the history of N95 mask popularity

N95 became popular in the "extreme period"

In 2003 SARS period, resembling a gas mask N95 respirator become the darling of the market.

Compared with the former two masks, this protective mask is much more professional in terms of dust protection. The N95 mask model is based on the U.S. standard, which classifies medical protective masks into three categories and nine models. N represents non-oily particles, and R and P type represent oily particles. Non-oily particulate matter includes coal dust, cement dust, acid mist, welding fumes, and microorganisms; oily particulate matter includes oil mist, soot, and coke oven smoke. Each model is divided into three filter efficiency levels, 95% , 99% and 100% respectively . The meaning of N95 is "filtering non-oily particles with a 95% efficiency dust mask."

China's dust mask standards are not divided so finely, but the N95 is still the minimum standard for such dust masks.

Now that the threat to human health in the atmosphere of the maximum particle diameter of 10 microns or less particulate matter (of PM10), in particular having a diameter of 2.5 microns or less particulate matter into the lungs (PM2.5). For these tiny particles, the filtration effect of N95 is worthy of recognition. In the production standard of N95 , the test sample as a particulate matter is a sodium chloride aerosol with a diameter of 0.1-0.5 μm, and a qualified N95 mask should have a filtration rate of more than 95% for this aerosol . So, if you wear the N95 or a higher-grade dust mask properly , even if the air quality index ( AQI ) reports heavy pollution, we can get a little more peace of mind when going out.

When wearing medical protective masks, it is necessary to ensure the fit of the face and keep the masks closed to perform a good filtering function. Breathing and inhalation tests should be performed after wearing to confirm that there is no air leakage. Reusable masks can be reused, but they should be replaced if any parts of the mask become broken, broken, lost, or feel increased resistance during breathing. Dust masks should not be washed and should be discarded after elimination.

Three, questions and answers about masks

Question 1 , what is the " N95 mask"?

In NIOSH's revised respiratory protection certification rules ( 42 CFR 84 ), " N95 " describes the filter grade instead of the mask / gas mask itself (mask / gas mask is a word in English). However, many known masks use N95 filter media, which are also known as " N95 masks."

Question 2 What exactly does the " N95 " stand for?

In the NIOSH test, the filter material that can filter out more than 95% of suspended particles in the air is given " 95 " grade, 99% or more is " 99 " grade, and the filter is 99.97% (essentially equal to 100% ) " 100 " level. The letters N , R, and P represent the resistance of the filter material to the oil droplets in the air (some oils can reduce the filtering efficiency of the filter material). N stands for pressure drop , R stands for resistance, P stands for Strong resistance.

After sorting and combining, you can get the following table:

Level Description

N95, N99, N100 can remove at least 95% , 99% , 99.97% of suspended particles, not oil

R95, R99, R100 can filter out at least 95% , 99% , 99.97% of suspended particles, a bit oil-resistant

P95, P99, P100 can remove at least 95% , 99% , 99.97% of suspended particles, quite ~ oil resistant

In other words, the practical meaning of " N95 " is that it can filter out at least 95% of suspended particles in the air , but it is not resistant to grease filter grades.

PS : NIOSH tests the filter media using a simulation of "worst-case" parameters, such as the use of particles with a diameter of about 0.3 microns that are most penetrating the filter media , and 85 L /min gas that simulates a higher operating intensity. Flow-rate, electrically neutral aerosol (which is not conducive to the use of electrostatic adsorption of suspended particles for filter media), etc., the filtration rate in any step of the test is not lower than the lowest filtration rate of this grade, and this gives the assessment of the corresponding grade . That's quite ~ strict!

Question 3 : Is a regular medical mask a N95 mask?

the answer is negative. Ordinary medical masks are not specifically designed to withstand suspended particles, and their protective performance is not as good as the N95 mask. Ordinary medical masks are used to block large particles (such as bacteria). Most of them have no effect on small suspended particles (such as PM2.5 ), and they also leak from the side when the user breathes. .

Question 4 , N95 masks have different sizes and styles?

Yes, there are many. If the mask and the face do not fit together well, you can easily create leaks when you breathe. The contaminated air will come in from there, so you have to try it out and choose the size and style with the highest rate of synchronization.

Question 5 , brother has a sexy bearded face, brother can use N95 mask it?

Anything that does not allow the face mask to fit snugly on the face, such as a long hair or a tie, can cause your mask to leak (Kuan Guan's tears). If your mask needs to fit tightly against your face, you'd better shave it. If you're a squeaky guy, you can wear a beard with a filter that covers the head (such as Resident Evil).

PS : The old American Institute of Occupational Protection really wanted to be thoughtful...

Question 6. Can anyone use a mask to protect?

No. Breathing with a mask is much more difficult than breathing freely. People with lung diseases such as asthma, emphysema, and elderly people may experience problems. All in all, it is better to consult a doctor before using it.

Question 7 , how long can I use my N95 mask?

There is no absolute exact time limit. In general, the main factors affecting the repeated use of the N series are the sanitary conditions of the mask, the damage conditions, and the degree of increase in respiratory resistance. For ordinary people, keep your mask dry and tidy. If it is bad or feels panting, then change it.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.