Air pollution is among the most severe menaces of modern times. An ever increasing level of industrialization, number of automobiles, chemical contamination of all kind result in the air that is hard to take in one’s lungs. You lock the front door with relief, close the windows and turn on the air conditioning…but are you safe in there? Unfortunately, the situation in closed spaces, including your fortress of coziness called home, is not much better. On the contrary, scientists claim air pollution is even greater indoors, as a result of modern energy-efficient technologies that additionally inhibit air circulation. However, a safe home that is devoid of air pollution is a mission possible through using efficient indoor air filters and purifiers. Before you open your wallet, you need to arm yourself with the knowledge to make sure you spend your money wisely.

How polluted is indoor air?

EPA and its Science Advisory Board (SAB) have ranked indoor air pollution among the top five environmental risks to public health. Studies of human exposure to air pollutants show that indoor levels of pollution may be two to five times higher than outdoor levels. Occasionally, it may reach more than 100 times. The fact that people spend about 90 percent of their time indoors makes the above numbers an issue of great concern. (1)

According to the World Health Organization (WHO), Sick Building Syndrome results in:

  • 14% decrease in productivity in the workplace.
  • 3% decrease nationwide in productivity.
  • Estimated monetary losses as much as US$60 billion.
  • US$10-23 billion lost in respiratory healthcare costs.
  • US$3-6 billion lost due to allergy and asthma cases.

What are the pollutants and what are the harmful effects on our health?

There are many factors that add to the buildup of harmful substances in the indoor air. Major causes for severe indoor air pollution include heating equipment (stoves, heaters), tobacco products, building materials and furnishings (asbestos-containing insulation, newly installed flooring, upholstery or carpet, pressed wood products), household cleaning detergents, personal care and cosmetic products, central heating and cooling systems, excess moisture, as well as outdoor sources.(2)

The effect of indoor air pollution on hеalth depends on the level of toxicity, concentration and exposure time to a specific pollutant or a combination of pollutants. It also may vary from person to person. The most common adverse health effect is the sick building syndrome (SBS). Its symptoms include uncomfortable or acute health effects such as irritation of nose, eyes and throat, skin ailments, allergies, and so on. (3)

Typically, the air in your home contains some or all of the following:

Volatile organic compounds (VOCs)

These include a wide range of chemicals (formaldehyde, naphthalene, paradichlorobenzene, chloroform, acetaldehyde, benzene), some of them may have short- and long-term adverse health effects. Products that can release organic chemicals make up a long list – paints, varnishes, wax; cleaning, disinfecting, cosmetic products; fuels made up of organic chemicals.

The concentration of VOCs indoors is found to be up to ten times higher than outdoors. (3)

The adverse health effects of VOCs varies – from high toxicity to none. They can cause eye, nose and throat irritation, headaches, nausea, fatigue or dizziness. Some studies link VOCs to adverse effects on respiratory health (4), damage to liver, kidney and central nervous system

and even cancer (5). Up to date, little research is done to make conclusions about what health effects occur from the levels of organics usually found in homes.

Particulate Matter

Particulate matter (or particle pollution) consists of solid or liquid particles suspended in air. Particles that are less than 10 micrometers in diameter are of particular concern. They are small enough for you to breathe them in. Once inhaled, they can even enter the bloodstream and cause damage to the heart, may affect lungs and in some cases cause serious health effects. Major sources of PM are indoor smoking, particles that originate from indoor sources, cooking stoves, fireplaces.(6)

Biological pollutants

Bacteria, viruses, animal dander and cat saliva, house dust, mites, cockroaches, pollen might be all around your home. Some of them may cause an increased risk for people suffering asthma, or people with compromised immune system. Symptoms of health problems caused by biological pollutants include: sneezing, watery eyes, coughing, shortness of breath, dizziness, lethargy, fever, and digestive problems. Controlling the relative humidity level at home might help inhibit the growth of some sources of biological pollutants such as mold, dust mites, bacteria.(9)


The main source of indoor radon is the radon produced by the decay of radium in the soil a house was built on. Soil gas containing radon enters a house through cracks and fractures in the foundations. Levels of radon can be quite high inside houses with poorly sealed foundations, built on high-permeability ground, even if the soil air has only moderate levels of radon (7) Radon is radioactive and is considered a leading cause of lung cancer in nonsmokers.(8)

Nitrogen Dioxide

Nitrogen Dioxide is a toxic gas, highly reactive oxidant and corrosive. Primary sources of Nitrogen Dioxide indoors are cooking stoves (especially gas stoves, unvented ones), indoor smoking, kerosene heaters. Nitrogen Dioxide can irritate lungs, as well as lower the resistance to respiratory infections, especially in young children. (9)

Carbon Monoxide

This odorless, colorless and toxic gas can be extremely dangerous if accumulated in high concentrations in a home and if one is exposed to it for a long time. It could be emitted indoors by unvented kerosene and gas space heaters, gas stoves, wood stoves, fireplaces, automobile exhaust from attached garages, nearby roads or parkings. At low concentrations, it causes fatigue in healthy people and chest pain in people with heart disease. Can cause flu-like symptoms that disappear after leaving polluted closed space. It may be fatal at very high concentrations.(10, 11)


75 percent of U.S. households used at least one pesticide product indoors during the past year. It is found that 80 percent of most people’s exposure to pesticides occurs indoors. Measurable levels of up to a dozen pesticides have been detected in the air inside homes. Exposure to pesticides is linked to Irritation to eye, nose and throat, damage to central nervous system and kidney, increased risk of cancer.(12)

What’s the difference between Air Filters & Air Purifiers?

While researching what type of air cleaning system to purchase you’ll surely be tangled in confusing terminology. Terms like “air filter” and “air purifier” are often used interchangeably. When in fact, they differ in terms of the size and type of pollutants they remove, as well as the mechanism they use to achieve that.

Air Filter (often referred to as Air Cleaner) is a device that removes pollutants using a mesh of some sort to trap particles. Air is forced through a filter and particles are physically captured by the filter. They are effective at collecting dust, especially the larger particles and pet dander.

Air Purifiers, on the other hand, sanitize the air, fighting airborne pathogens that cause allergies and sickness. They use technologies like emitting negative ions, ozone, utilizing heat or UV.

The most effective air purification devices in the world, however, take advantage of both air cleaning and air purifying technologies to address a wide range of indoor air quality issues.

What are the different technologies employed in removing pollutants in the air?

There are so many technologies and air filtering solutions out there, but not all are equally effective and some may be even bad for your health.

The best air cleaning devices are multi-stage filtration systems that typically feature a combination of two or more of the following treatment methods:


It’s purpose is to capture large pollutants like hair dander and larger dust particles. It is usually used in combination with a HEPA filter to stop largest particles before they reach the HEPA. They are usually made out of woven nylon or foam.

Activated Carbon

Activated Carbon Filters or sometimes referred to as Gas-phase air filter, uses a chemical reaction called adsorption (not absorption) to screen out toxic gas molecules like cigarette smoke, gases, odors, mildew. Some activated carbon filters can also remove volatile organic compounds (VOC’s) like formaldehyde and pesticides. They contain a chemical known as a chemisorbent, which traps VOCs in the filter or makes them harmless. Typically, not used on its own, but paired with a HEPA.

HEPA (OLD) replaced with Nano Coil Technology

High-efficiency particulate air (HEPA) filters are claimed to be 99.97% efficient in removing particles 0.3 microns in size or greater (dust, pollen, mold spores). A non-petrochemical, medical grade HEPA filter would constitute a good choice.

HEPA filters are made of randomly positioned fibers to form a mesh of narrow passages. The air passes through the twists and turns,particles are trapped, clogging holes and making the grid even smaller. This means the filter gets more efficient with ongoing use. HEPA filters do not remove toxic gas from the indoor air and they need to be combined with other technologies.

Nano Coil Technology which is the modern replacement of HEPA removes an even greater percentage of airborne pollutants – 99%. It reduces bacteria and kills cold and flu viruses. It’s five times better than HEPA in clearing the air of pet hair, fur, dander, dust, and mold. This technology cleans microscopic particles down to 0.05 microns.

UV-C Light

Ultraviolet radiation from UV lamps is used to destroy the DNA of biological pollutants, including viruses and bacteria. The same technology is used by hospitals for sanitization. It destroys 99.9% of germs, causing colds or flu.

Caution! Avoid Filtration Technologies That Emit Ozone

Ozone is considered a lung irritant. So, while considering the purchase of a home or office air purifier, avoid systems using some of the following technologies. Especially to be avoided by people with respiratory conditions.

  • Electrostatic precipitators screen out pollutants by charging them as they pass through. Then the impurities cling to an oppositely charged metal plate. The harmful particles are collected on a plate that can be simply washed, eliminating the need for frequent or expensive filter change. But this convenience doesn’t compensate for the fact that they produce ozone as a by-product.
  • The negative ion generator works by changing the electrical charge of its surroundings. Negative ions attract positively charged particles floating in the air. They stick together making impurities too heavy to stay in the air, so they drop down and can be removed through conventional cleaning procedures like vacuuming. One problem is particles can stick to walls or furniture item and later circulate in the air again since they are not filtered. The second issue is they may emit harmful levels of ozone as a byproduct.
  • Ozone generators emit ozone, a toxic gas, that reacts readily with other chemicals that may be in the air, forming new compounds. Manufacturers of ozone generators suggest that ozone will render almost every chemical contaminant harmless through this chemical reaction. However, studies have shown that using ozone generators as indoor air purifiers is not only inefficient but is harmful to health. Ozone can produce compounds that can be more dangerous than the ozone itself. In addition, ozone does not remove particles (e.g., dust and pollen) from the air, including those that cause most allergies. These purifiers should be avoided completely.

Thermodynamic Sterilizing System (Airfree TSS Technology) view here

Thermodynamic Sterilizing System is a patented new technology integrated in AirFree Air Purifiers
Thermodynamic Sterilizing System is a patented new technology integrated in AirFree Air Purifiers. Photo Credit: AirFree Air Purifiers

Thermodynamic Sterilizing System is a patented new technology integrated into Airfree Air Purifiers exclusively. It utilizes hot air (heated in an inner chamber that reaches a core temperature of 400 degrees Fahrenheit) to eliminate airborne mold, bacteria, viruses, pollen, dust mites and other allergens. It is claimed to destroy 99.99% of all microbiological agents which pass through the air cleaning product’s sterilizing ceramic core. The good thing about this technology is is doesn’t emanate any harmful gases or other substances uses no filters (no need to change them) and is pretty silent while working. The only drawback is it doesn’t remove chemical pollutants.

PhotoCatalytic Oxidation TiO2

Typically uses titanium dioxide as the catalyst in combination with ultraviolet (UV) light. When TiO2 is energized by UV, its electrons interact with water molecules (H2O) in the air, breaking them up into highly reactive compounds. The latter interacts with organic pollutant molecules (VOCs), breaking apart their chemical bonds and turning them into harmless substances. Unlike filters that trap pollutants, PCO systems transform the harmful chemicals and destroy them.

However, are not designed to remove particulate pollutants. (13) In addition, they produce some amounts of ozone and it’s also under debate if the substances produced during the process of PhotoCatalytic Oxidation could be as dangerous (or more) as the pollutants themselves. (14)

The most advanced models have multiple metals in the catalyst film and a three-dimensional structure wrapped around the UV emitter.

Thermocatalytic oxidation MnOx

A nanocatalyst technology using manganese oxide (MnOx) as a catalyst. It does not need UV lights to function. The oxygen from MnOx interacts with VOCs on the catalyst surface. It is suggested that it regenerates itself by replacing its lost oxygen with O2 from the air stream.

The manganese oxide (MnOx) based filter targets specifically formaldehyde. It works on other VOCs either, but has a lower oxidative-potential than TiO2, limiting its realm of VOCs to those easily oxidized (i.e. formaldehyde and acetaldehyde). This method controls harmful by-products from TiO2, thus, making it a good supplement to Photo Catalytic Oxidation.

Photo Electrochemical Oxidation (PECO)

Photo Electrochemical Oxidation (PECO)
Photo Electrochemical Oxidation (PECO) Air Cleaner/ Photo Credit: Molekule

An innovative nanotechnology capable of destroying (not filtering) airborne bacteria, viruses, mold, allergens, and volatile organic compounds (VOCs). During the PECO process incident light is used to trigger a chemical reaction (oxidation) on the surface of a nanoparticle coated filter (semi-conductor). As a result, hydroxyl free radicals are created. They oxidize pollutants at the surface of the filter rendering them harmless.

The product that incorporated this process for the purpose of removing a wide spectrum of airborne contaminants is called Molekule. Though pricey, the company manufacturer claims it is way more efficient than HEPA and carbon filters. It is said to completely eliminate pollutants up to 1000 times smaller than what a HEPA filter could screen out. Independent laboratory tests verify that the Molekule safely remove air pollutants and that byproducts of the system are completely harmless elements.

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