Many northern cities will have serious haze in cold winter. When going out in haze weather, masks have become standard for many people. Can masks really prevent haze? What do we need to know about protective masks?
1、 What is an anti haze mask?
At present, the frequently mentioned anti haze mask is basically a professional protective mask, which can effectively protect all kinds of granular and other air pollutants suspended in the air and provide respiratory protection for the wearer. Different countries and regions have different protection standards, which are generally clearly marked on the mask package for distinction.
(1) Development traceability
In 1849, the lung protector (dust mask) invented by Lewis P. Haslett won the first patent for protective mask in the history of the United States, which uses one-way valve and wet wool to filter dust, etc. Later, Hutson Hurd improved on the basis of Haslett's invention to form today's Cup mask, which has been used until the 1970s.
With the growing interest in air purification devices, John Stenhouse later invented a respirator that can effectively filter toxic gases. For the first time, charcoal powder was used to filter toxic gases. The shape is more similar to today and can be replaced regularly, but the mask was still made of metal at that time.
In the years after World War I, countries such as the United States and Britain faced the most serious air pollution in history. In December 1952, London suffered a five-day smog pollution, resulting in 12000 deaths and 100000 respiratory diseases. It made people aware of the bad consequences of air pollution at that time, and directly catalyzed the later development of air purifiers and haze protective masks.
In the modern sense, dust masks made of non-woven materials originated in the United States in the 1960s and 1970s. The well-known American 3M company also began to design and produce dust masks from that period.
(2) Why do we need anti haze masks?
This is a very heavy and unavoidable problem, especially in the current situation of the continuous expansion of China's haze area.
2、 What do you need to know about protective masks?
(1) Know what kind of mask you need
1. One problem needs to be clarified: haze ≠ PM2. 5。 PM2. 5 is the general name of solid particles with a diameter of less than or equal to 2.5 microns in the air, and the composition of haze is very complex. The definition of haze by China Meteorological Administration is that a large number of smoke, dust and other particles are suspended in the air, making the sky turbid. The common disposable medical masks, cotton masks and activated carbon masks on the market may have some effects on dust, peculiar smell or large particles in the air, but for PM2 5 and other serious pollutants still need relatively professional protective masks.
2. The main component of haze pollution is non oily particles. Ordinary Dust Haze masks can be selected for daily travel, that is, masks marked with 'n' and 'kn'. People who are often exposed to oily particles such as oil smoke, oil mist and asphalt smoke can appropriately choose masks marked with 'p', 'R' or 'KP'.
(2) Common filtering standards for protective masks
Fine particles (PM2.5) in the air are divided into oily particles and non oily particles. The standards for protection levels in the United States, the European Union and China are different:
1. American Standard (standard formulated by NIOSH, National Institute of occupational safety and health)
That is, common concepts such as N95, n99, R95 and p95. N stands for protection against non oily particles, R stands for protection against oily particles or non oily particles (more than 8 hours are not recommended for oily particles), and P stands for protection against oily particles or non oily particles (follow the manufacturer's recommendations for oily particles); 95 / 99 / 100 represents the protective filtration level. When tested with 0.3 micron particles, the barrier efficiency is more than 95% / 99% / 99.97%, so N95 is a kind of mask rather than a specific commodity. For PM2 5 particles, or some diseases spread through the air, can be achieved by using N95 mask.
2. European standard (standard formulated by Cen, an authoritative European standard setting organization)
There are occasional labels in the domestic mask market, mainly including ffp1, FFP2 and ffp3. Both are suitable for filtering oily and non oily particles, but the effect of protecting oily particles is not obvious, and the price is slightly higher. In use, it can be considered that FFP2 is about equal to N95 standard or even higher.
3. National standard (China gb2626-2006 standard for respiratory protective articles)
It is mainly divided into kn and KP. Kn is suitable for filtering non oily particles, and KP is suitable for filtering oily and non oily particles. In terms of actual effect, KP with the same mantissa is lower than P and higher than R, i.e. R100 & le; KP100≤ P100。