Air quality and the different forms of air pollution

Indoor air quality is a subject that has picked up a great deal of speed in recent years. General consensus had us believing that outdoor air is more polluted than indoor air, but the opposite is proving to be true.

A 2004 survey carried out by the Indoor Air Quality Observatory discovered that indoor air pollution has many causes. The survey, having tested 560 homes and 1,600 people interviewed, had several surprising findings:

  • Most homes experience some degree of indoor air pollution (particularly pollution by formaldehyde, which is found almost everywhere), some even showing significant concentrations of multiple pollutants
  • Indoor air is much more polluted than outdoor air (5-10 times more!)

Considering the fact that we spend 80-90% of our time in indoor spaces (between our homes workplaces, forms of transportation, etc.), these findings are concerning to each and every one of us. It is no wonder why why the topic of indoor air pollution has become a major public health issue.

What are the major sources of indoor air pollution?

    Many sources can be responsible for causing indoor air pollution. One must look at the origins of the air pollution to understand exactly from where it comes: it can be generated by the occupants themselves, by equipment present within the accommodation, or by the foundations and/or materials within the accommodation itself (construction, decoration, furnishings, etc.).

    Indoor pollution can generally be classified into three types:

    Particulate pollutants (or fine particles)

    Fine particles may be too small to visualise, yet we inhale them all day long. Fine particles can come from many different materials including smoke, soot, pollen, and other allergens such as dust, hair, dandruff, etc. Performing certain activities in the home create these fine particles, sometimes in large quantites, and promote their suspension in the air. Some of these activities include DIY projects, cooking, cleaning, using tobacco, and lighting candles.

    Fibres can also be a source of fine particles. Some examples may be fibres of plant origin (cellulose, hemp, sisal, jute, etc.) or of mineral origin (asbestos, fibreglass, and mineral wool). Both of which may be responsible for producing allergens.

    Finally, let us not forget a major culprit of fine particle production: heating with wood or the combustion of fossil fuels (and in particular exhaust gases). These can lead to serious fine particle exposure.

    Chemical pollutants

    These pollutants are as abundant as they are common in indoor air. Some examples are:

    Carbon monoxide or CO. We all know this one well as “the silent killer”. Carbon monoxide is colourless, odourless, and deadly when present and inhaled at high concentrations. This toxic gas is released into our homes in substantial quantities when devices used for heating or hot water are poorly maintained and/or used in a confined space that is poorly ventilated and oxygen-depleted. Ventilation is crucial!

    Volatile organic compounds or VOCs. These are emitted by every-day products that we use in the home including paints, solvents, furniture, DIY work, and decorations. After the installation of a new piece of furniture or fabric in the home, formaldehyde (a dangerous VOC) can be released for one to two years. Fragrances or sanitising sprays can also be a source of VOCs, although we may not naturally associate products that smell good with something that could be potentially dangerous for our health. New car smell is another scent that is a notorious source of VOCs. The list of VOCs contains hundreds of compounds, but some of the most infamous are formaldehyde (the most concerning in indoor air), organic solvents, glycol ethers, and hydrocarbons including benzene. Some VOCs are so dangerous to our health that they can cause cancer.

    Semi-volatile organic compounds or VOSCs. These are mainly found in materials used for maintenance of the home including coatings, plasticisers, products used for treating wood, biocides, and flame retardants (among others). A few of the components that can cause harm to humans include phthalates, PAHs, bisphenols, musks, organophosphates, and pyrethroids.

    A few more dangerous chemical pollutants worth mentioning are nitrogen oxides (NOx), sulphur dioxide (SO2), and pesticides (insecticides and fungicides).

    Biological pollutants

    These pollutants are those that come exclusively from living organisms (animals, plants, moulds, etc.). They are generally separated into three major types:

    Infectious agents (bacteria, viruses, toxins) usually come from the individuals living in the dwelling. They also may develop in and around certain equipment inside the home (water heating units, poorly maintained ventilation, and air conditioning units, to name a few). Once moulds grow, spores that emerge can cause dangers to our health once inhaled.

    Allergens can be caused by many sources and affect everyone differently. The usual sources that emit allergens are moulds, animals, plants, insects or dust mites.

    Moisture is classified as a source of pollution because it directly leads to mould growth. Some particularly humid places in the house where moulds are common are the kitchen (where we cook and wash dishes), the laundry room (where we wash and dry clothes), and the bathroom (where we wash ourselves). Poorly ventilated, damp rooms are the first offenders to harbouring mould. However, moisture can simply be associated with wherever humans breathe! With the first sight of mould, swift action must be taken as their spores can quickly proliferate and invade the entire home.

      Why is fighting against indoor air pollution so important?

      We have discussed the most common sources of indoor air pollution, but what can poor indoor air pollution actually do to our health?

      Indoor air pollutants can access the body through two inlets: the first is being directly absorbed through our breathing, and the second is through the skin. Since we spend nearly 99% of our time in indoor spaces, this means that we are almost always exposed. This leads to repeated and long-term exposure to “cross-pollutions” (and therefore, potentially, the cocktail effect).

      Short-term effects

      Physical discomfort is usually one of the most immediate results of short-term exposure or inhalation of large quantities of pollutants. Symptoms may include irritation of the eyes, nose, and throat. The pollutants themselves can be responsible for generating unpeasant odours, which can be bothersome.

      While many symptoms caused by short-term pollutant exposure are mild, more severe symptoms may and do occur. Some of these symptoms include headache, cough, nausea, asthma attacks, and skin and mucous membrane irritation. These can be tell-tale signs of air quality degradation in your living space (potentially pointing to the presence of VOCs, biocontaminants, and/or faulty ventilation, among others).

      Long-term effects

      Repeat and consistent exposure to pollutants, even in low doses, can seriously impact our health, leading to chronic and/or serious illnesses. It can be difficult to draw direct causation between the diagnosis of cancer and repeat exposure to pollutants. However, certain pollutants are definite direct causes of cancer. Some of these are tobacco, formaldehyde, radon, fine particles, and benzene.

      This represents a staggering 3.8 million people annually who die prematurely from diseases attributable to indoor air pollution on a global scale (27% pneumonia, 27% ischemic heart disease, 20% chronic obstructive pulmonary disease [COPD], 18% of stroke and 8% of lung cancer).

      The APQAI (Association for the Promotion of Indoor Air Quality) has published several studies demonstrating the connection between exposure to certain toxins or particles and mortality. Conversely, a multitude of studies has shown an increase in life expectancy for people not exposed to these pollutants.

      Fight air pollution with Eoleaf

      According to the Ministry of Ecological Transition, indoor air pollution costs us not only our health but an enormous sum of money, too. The financial cost of poor indoor air quality is estimated at 19 billion euros per year. Combatting air pollution is a major undertaking, one that requires wide scale implementation of health and economic measures. Solutions are starting to pop up in both public and private places including schools and homes.

      In establishments that cater to sensitive populations, the Indoor Air Quality (IAQ) action plan of the Grenelle II law has made air quality monitoring mandatory in such locations to combat the massive risk of indoor air pollution to these vulnerable individuals. These include kindergartens and elementary schools since 1 January 2018, and leisure centres, colleges, and secondary schools since 1 January 2020.

      We are all concerned and directly impacted by the dangers of poor air quality, and we all have our part to play in battling it! For those who confront pollutants on a regular basis, it is important to act effectively and with the appropriate tools. Some good habits to follow are:

      • Ventilate your home and workspace regularly, particularly in the mornings and evenings when outdoor allergens are at their lowest
      • Completely avoid any products that generate VOCs and other chemical pollutants at home, in the office, and in the garden
        • When making purchases, always be conscious and choose eco-friendly, natural products and/or products without or with low VOC emissions
        • Avoid room fresheners/fragrances, insecticides, and household bactericides
      • Try to limit your use of thermal combustion cars
      • During periods of cold weather, do not overheat your home! Maintain your boiler or wood stove at a temperature of 18 to 20 degrees

      An excellent, complementary solution to these measures is to purchase and employ an air purifier. Eoleaf, a French company specialising in air purification technologies, offers high quality air purifiers that use scientifically-proven filtration and depollution methods to reduce indoor air pollution. This powerful device focuses on the three main sources of air pollution: particulate, chemical, and biological.

      Suitable for needs at both the individual and professional scale, Eoleaf air purifiers have found success in hospitals, medical clinics, doctors’ offices, hairdressing salons, and nail salons, to name a few. Our air purifier make the perfect indoor air-cleaning companion.

      How does an air purifier work?

      An air purifier draws in ambient air via a motor-driven fan. The air then passes through one or more filters and is exposed to one or more pollution control methods before being released back into the room.

      At Eoleaf, our products contain eight different filters to create a purification system powerhouse. It all starts with a multilayer filter.

      First, as a first line of defence, the pre-filter captures larger particles (those larger than one micron like dust, hair, dander, etc.).

      The next step is a bamboo fibre filter through which all the remaining particles pass. This is a strongly antibacterial natural material and is soaked in lysozyme, an antibacterial protein.

      You will then find our HEPA H13 filter. This step focuses on filtering all fine particles (up to PM0.01), allergens (pollen, mites), and germs (bacteria, viruses, moulds, spores). Thanks to our HEPA H13 (European standard EN 1822 and EN ISO 29463) filter, 99.97% of particles with a diameter greater than or equal to 0.01 μm are eliminated!

      The next-to-last step in our filtration process consists of an activated carbon filter. Activated carbon is a material that has a porous structure and is a very commonly-used method in various types of filtration (particularly water filtration). It is also seen in cigarette filters, aquariums, and even atomic shelters which attests to its effectiveness. This naturally-occurring substance specialises in fixing to and retaining pollution particles (while simultaneously eliminating bad odours).

      The final layer of the filter is photocatalysis. This is a technology that produces molecules that react to the pollution particles present in the air, quickly and effectively degrading them. Additionally, this is all done without any ozone emission. It is quite the weapon against chemical pollution!

      Following filtration come two methods of depollution. First in line is the UV lamp. This is a sterilisation method that acts against all microorganisms and germs. UVCs are known for their ability to eliminate biological pollutants, and they are commonly used in hospitals for their effectiveness and safety. Additionally, they have proven effective against COVID-19, SARS, and MERS.

      The second depollution step and last step overall in bringing you clean air is none other than ionisation. By diffusing negative ions into the ambient air, the goal is to counter any pollution particles still present (which are positively charged). This technique works against any fumes and/or fine particles still present in the air and is a proactive technique, performing its job outside the device as opposed to inside like the previous steps.

      Eoleaf’s air purifiers deliver skilfully-designed filtration and depollution of your air. They can guarantee an improvement in the quality of the air in your room, leaving you with healthy and breathable air free of harmful pollutants.



      1. Ministry of Ecological Transition: Indoor air quality. Referenced from
      2. Atmo Nouvelle-Aquitaine: What are the sources of indoor air pollutants? Referenced from
      3. The notebooks of sustainable development: Indoor air pollution. Referenced from  
      4. Anses: Indoor air quality. Referenced from
      5. Ademe: Practical guide - healthy air at home. Referenced from
      6. Apqai: Indoor pollution - let's be aware of it. Referenced from
      7. My eco-comfort house: Indoor air quality - indoor pollution is always higher than outdoors. Referenced from
      8. WHO: Indoor air pollution and health. Referenced from

      Eoleaf's range of air purifiers

      1 of 4