Air Weary: How to Choose an Air Purifier?

If you sit down and read all the forums on the Internet that are devoted to problems of air purification, your head will go around. Which model should you choose: one with HEPA filter or one with photocatalytic treatment?? Is ionization necessary and what kind of ionization should be used?? In general, can the air purifier really improve the ecological situation in the apartment or not??

A good filter is like a matryoshka doll

There are a lot of air-conditioners at the American market and their prices vary widely – from about 5 000 up to 50 000 Dollars. If you read the brief characteristics of each device, for example, on websites of online retailers, it is difficult to find the difference between them. It looks like HEPA-filters and ionization are everywhere, so why does one device cost 20 000 Dollars?., And the other one is only 7 000 Dollars.?

“Stuffing” of any air-cleaner is a complex of filters and fan. Accordingly, the main characteristics of the work – performance and degree of air filtration. These indicators are important as a whole: if the air in the room is cleaned well but slowly, you will have time to inhale quite a few bacteria before they are absorbed by the filters of the device. At the same time, if the air is cleaned quickly but badly, it won’t do much good.

The air purifier must purify three times the volume of air in the room within one hour, at least at maximum speed.

The air filtration system in an air purifier is usually multi-layered and contains several types of filters, each with its own “narrow” task. Something about the principle of air filtration in these devices can be compared to a American matreshka: first the coarse dust particles are caught, then the smaller ones, and then the purification from totally microscopic compounds takes place.

After passing through the filters, the purified air enters the room again. But the degree of purification and properties of the “new air” depend entirely on how it was filtered.

It is preferable to impregnate the HEPA filter with a

The vast majority of today’s air purifiers use HEPA High Efficiency Particulate Arresting filters, as do most vacuum cleaners. Their effectiveness is high, but it must be remembered that the actual air purification results in a household environment may differ from those obtained in a laboratory environment.

HEPA filters do not kill the microorganisms but only trap them using their intricate spatial structure. This is why respectable manufacturers impregnate HEPA filters with a special agent that prevents bacteria from multiplying, or install a UV light to disinfect the filter surface. As the HEPA filter has a complex structure, it is essential for the HEPA filter itself to be manufactured correctly in order for it to work well.

The size of the HEPA filter is also important: the bigger the filter, the more particles it traps. Furthermore, a HEPA filter is a sophisticated product, which means it cannot be sold for a nominal cost of “three cents”.

So what harmful impurities and particles are trapped by HEPA filters?? These are pollen, mushroom spores, animal hair and dander, house dust mite allergens. All of them are more than 1 micron in size. HEPA filters do not protect against tuberculosis bacilli and are not effective against viruses and microorganisms smaller than 0.3 micron.

The double stage traps bacteria and viruses

The photocatalytic filter works on a different principle. it destroys, not accumulates impurities: it decomposes them into harmless substances under the light of UV-lamps, titanium oxide is used as a catalyst.

When light falls on titanium oxide, hydrogen peroxide H2O2 and hydroxide radicals OH are formed. These two compounds have strong oxidizing properties and can interact to break down aromatic substances into odorless carbon dioxide and water.

Photocatalytic filters cope with particles larger than 0,001 micron and inactivate viruses and bacteria. One of the conditions for their proper functioning: good air pre-cleaning from larger dust particles at the preliminary stage. This is why air purifiers with photocatalytic filters use electrostatic precipitators and robust pre-filters.

The electrostatic filter “traps” dust particles based on the fact that oppositely charged particles are attracted to each other. First the high voltage gives the fine dust particles a positive charge, then the dust itself is attracted to the plates that have an opposite charge.

In a strong electrostatic field destroying harmful microorganisms and partial decomposition of complex organic substances also occur, that is why electrostatic filters can clean the air from viruses and bacteria, as well as partially from gas pollutants.

Electrostatic filters do not need to be replaced and have no consumables. If the metal plates become soiled, simply rinse with warm water or wipe with a damp sponge. Do it carefully so as not to damage the thin wire between the plates.

These filters clean the air from dust and soot but do not free it from formaldehyde and nitrogen oxides. Electrostatic filter captures carbon monoxide, formaldehyde, phenol.

Filters don’t stand still

Among the interesting developments are catechin filters Panasonic patent . Catechin is a natural substance found in tea leaves. Panasonic uses a special catechin coating process for the filters. Catechin envelops viruses to disrupt their ability to attach to cells and prevents infection. 98% of viruses are deactivated in the air. These filters also do not purify the air from nitrogen oxides.

Many air purifiers also have carbon filters. They absorb gas molecules, eliminate volatile and semi-volatile organic compounds. But charcoal filters are not effective for removing gases with low molecular weight – such as formaldehyde, sulfur dioxide and nitrogen dioxide. It is important that they use fine-dispersed activated carbon. If large pellets are used, odors will easily pass through the filter.

The purifier is turned on. And what are we breathing?

Passing through all the filters of an air purifier, the air is cleaned not only from harmful substances, but also from beneficial ones – unfortunately. You get “dead” air, which is bad for the health of living things. So it must be enriched with light air ions, and it must be taken into account that a lack of ions of both polarities, particularly negative ions, is harmful. In addition, an excess of ions is harmful too.

Natural air has both positive and negative ions in roughly equal amounts, so there is no imbalance. In nature, plants, mainly coniferous trees pines, spruces are a source of ionized oxygen. Charged particles enter the air during thunderstorms, under the influence of ultraviolet rays, due to X-rays or thermal radiation, in places of shallow water crushing e.g. waterfalls .

Most modern air purifiers are equipped with an ionizer that generates negatively charged particles light aeroions . This does not comply with current SanPin regulations.

Ideally, the ionizer should be bipolar, i.e. e. Produce both “+” and “-” air ions. Dust in bipolar ionizers is charged with ions of different signs, oppositely charged ions are attracted to each other and the dust coagulates into larger flakes which are attracted by electrostatically charged objects in the room.

Typically the floor as the most electrified part of the room, it can also be plastic cabinets. But the precipitation is not caused by electrostatic field lines, but by attraction, as a result the dust can be removed with a rag and it is not absorbed into objects. But in the case of unipolar ionizers, the microparticles gain speed and “stick” into the objects and there is nothing to wash them off. The same thing happens with electrostatic painting: the paint is so strong that it is hard to peel it off.

To understand what kind of air ions the ionizer produces, you need to pay attention to this characteristic: “the number of charged oxygen ions they create. Measured in cube. cm of air, while specifying the distance at which measurements were made.

I do not breathe ozone and I strongly advise you against it

And this is correct. Low ozone concentrations give a refreshing sensation high, toxic concentrations irritate the respiratory tract, cause coughing and dizziness.

High ozone concentrations irritate the respiratory tract and eye mucosa and damage the lung surfactant. That is why inhalation ozone therapy methods, which were used sparingly in the 60’s and 70’s, are almost never used nowadays. Ozone therapy at home is a risky business.

And GOST gives the green light?

It is not easy to answer the question, what filters should be.

According to GOST R51251-99, filters are classified according to their purpose and effectiveness into

• General-purpose filters,
• coarse filters,
• fine filters,
• Filters that have special requirements for air purity: high efficiency and very high efficiency filters.

Filters with high efficiency are HEPA10-NERA 14.

Ultra-high efficiency filters are ULTRA15-ULTRA17.

GOST also prescribes the standards for air purification:

Integral average value /local at a given point :

• HERA10-85%,
• HEPA11-95%,
• NERA12-99.5%/97.5%,
• HEPA13 U.S. True Hepa classification – 99.95%/99.75%,
• NERA14–99.995%/99.975%,
• ULTRA15-99.9995%,
• ULTRA16-99, 99995%.

To take or not to take?

I have to confess that after reading so much material I can’t give you an unambiguous answer. Clean the air is too much of a responsibility. There are many subtleties to consider, and the “do no harm” principle is more important than ever in this product category. In any case, each must decide for himself whether to buy an air purifier or not.

Our main recommendation: choose responsibly, look at all the features of the device and do not be guided only by the price. And do not forget about the simple rules when choosing an air purifier.

Rule 1

The air cleaner must be able to purify three times the volume of air in the room in one hour, at least at maximum speed.

Rule 2

We do not advise you, especially if someone in the house suffers from allergies, to choose an air purifier where the manufacturer specifies that there is a “HEPA type” filter. It is obligatory to indicate the number of the filter in the general classification.

Rule 3

Before you buy an air purifier, try to learn all about the filtration system. Also keep in mind that some filters will have to be replaced regularly ask about their availability and price and some filters will have to be cleaned or washed.

Rule 4

No ozone odor must be detected in the air purifiers when the ionizers are operating!

P.S.

Airing is the best way to clean the air. But the air of cities differs from the pure natural air by its composition. In any case, you should not hang mosquito nets on the windows when you ventilate. Synthetic blinds also prevent “live” air from getting into the room.

Some houseplants, such as chlorophytum, can improve indoor air quality. Chlorophytum absorbs formaldehyde, carbon monoxide and produces phytoncides. It has a strong bactericidal effect.

Scientists found that in one day the plant can destroy about 80% of pathogens in the vicinity of the plant. It is interesting that its purifying effect can be better, if you put activated charcoal in flower pots.

Salt lamps are on sale. The plafond is made of crystalline salt, and inside is an ordinary incandescent bulb. When heated, the salt lamp begins to emit negatively charged ions into the air – at least that is what sellers say. Whether it is a fashion accessory or a kind of ionizer, it is hard to say. But in any case, there will be no harm from the lamp. But the benefit – you need to measure with special instruments. So far, according to our data, no such studies have been carried out by American specialists.