Did you know that according to the US Environmental Protection Agency (EPA), indoor air pollution is among the top five environmental health risks?  

We're all more aware that it’s harmful to breathe polluted air when we’re outside. But do you ever consider air quality when you’re indoors?  

We spend the majority of our time indoors, whether that’s at home, work, school, or when we visit cinemas, shops, or restaurants. Since the beginning of the COVID pandemic, we’re spending even more time at home, so air quality is an even bigger concern. 

Indoor air pollution is the dust, dirt, and gases mixed with the air inside buildings that can be harmful to breathe in. These contaminants can lead to lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), and even lung cancer.  

So how can you be sure you’re removing unwanted and often harmful pollutants from your home or office?  

The simplest way to address this problem is to control or remove the source of the pollutant and ventilate your home with clean outdoor air.  

However, this method is not infallible. You’re limited by external factors including weather, outdoor noise, and potential contaminants from outside.  

This is why the use of an air purifier can be recommended in some cases. These cleaning devices are intended to remove pollutants from your home or office when it is not possible to put in place full ventilation.  

Often air cleaning devices are designed to be installed in the ductwork of a home’s central heating, ventilation, or air-conditioning (HVAC) units. Here they can safely and efficiently clean the air in the whole building. However, it is also possible to purchase portable air cleaners that work to purify the air in a single room.  

What are indoor air pollutants? 

Indoor air pollutants generally fall into two categories: 

Particulate matter 

This includes dust, pollen, animal dander, smoke, dust mites, moulds, bacteria, and viruses. It can also include particles generated from combustion appliances such as cooking stoves. 

Gaseous pollutants 

This includes pollutants generated from combustion processes, such as gas cooking stoves, vehicle exhausts, and tobacco smoke. It can also include by-products from the use of products such as cleaning fluids, adhesives, paints, and varnishes.  


Micro-organisms are simple forms of life, including bacteria, fungi, algae, viruses, archaea, and protozoa that exist in the home air. They’re naturally occurring and exist on the outer and inner surfaces of the human body as well as populating soil, water, and the air. However, in number, they are not conducive to clean air so it is recommended to use an air purifier to remove them from the atmosphere. 


As you may surmise from the name, allergens are pollutants such as dust and pollen that exist in the air and can cause allergic reactions, such as irritation to the nasal passages and respiratory system, and in some cases irritate pre-existing conditions such as asthma and COPD. The best way to alleviate these symptoms is to remove the allergens from the air using an air purifier that’s certified to handle particulate matter that can trigger allergies. 

What type of air purifier do I need, and what will it remove?  

The type of air purifier you choose matters, as some are engineered to perform specific tasks. If there is a specific type of pollutant that you are looking to remove, then it’s vital to choose the right type of air purifier for the job.  

Let’s take a look at what types of air purifiers work with certain types of pollution. 

Particle removal  

If you’re interested in removing pollutants such as dust, pet dander, and pollen from the air, then two types of air cleaning devices are well-suited to this task - mechanical air filters and electronic air cleaners.  

Mechanical air filters, such as high-efficiency particulate air (HEPA) filters, remove potentially harmful particles by capturing them on filter material to remove them from the air. 

Electronic air cleaners, such as electrostatic precipitators, work by passing air through an ionization device. This gives particles an electrical charge. These charged particles are then trapped on an oppositely charged flat plate for removal. 

You may also consider an ion generator. This operates using a process similar to other particle remover units, but instead of collecting the charged particles, they fuse charged ions to airborne particles. This means they can accumulate on nearby surfaces, such as walls or glass, for easy cleaning and removal.  

Gaseous pollutant removal 

Gas-phase air filters work to remove one or more gaseous pollutants from the airstream. It’s important when choosing a gas-phase filter that you pick one which removes the type of gas pollution that you want to target. This type of air filter tends to work specifically on one, or a limited number, of gaseous pollutants. This means that they will not remove all air pollutants in the home, only the ones which the filter was designed to remove. 

Gas-phase air filters work by using an absorbent material, such as activated carbon with its high surface area, to process the pollutants and remove them from the air.  

These are the most common methods of air purification; however, other air purifiers do exist. 

  • UVGI (ultraviolet germicidal irradiation) cleaners use ultraviolet radiation from UV lamps to destroy biological pollutants such as viruses, bacteria, and fungal organisms.
  • PCO (photocatalytic oxidation) cleaners also use an ultraviolet lamp, combining this with a catalyst that reacts with the light. These cleaners are designed to destroy gaseous pollutants by converting them into harmless products. However, their use might create by-products that can be harmful. Care should be taken to check the harmlessness of such devices.
  • Ozone generators use UV light or an electrical discharge to purify the air. However, as they intentionally discharge ozone, a lung irritant that can cause adverse health effects, they are unsafe to use indoors.

How do I choose an air purifier? 

When it comes to choosing the ideal air purifier for you, it’s important to first consider what type of pollution you are removing, and what type of purifier is best suited to that situation.  

For example, if you are trying to remove pet dander from your environment, it would not be appropriate to use a gas-phase air filter. You would experience better results by using a mechanical air filter or an electronic air cleaner. 

Consider mechanical or HEPA air filters, ion generators, or electronic air cleaners as described above.  

It’s also vital to consider the performance of air purifiers and how this is measured. 

How is an air purifier measured? 

Air purifiers are tested using a specially designed test rig that measures the efficiency and the airflow rate of the devices. 

The efficiency of the air cleaner under test is measured against different types of contaminants. These are: 

  • Particles, such as oil mist
  • Gases
  • Cat allergens
  • Micro-organisms, including types of bacteria and fungi

The air purifier units are placed in a chamber, which is supplied with a stream of air containing the pollutants. As each pollutant enters the chamber and passes through the purifier, the concentration of the contaminant in the purified air is tested.  

Tests are also run to determine the purifier’s: 

  • Airflow rate 
  • Electrical power consumption
  • Sound power level

These measurements form the basis of the French standard NF B44-200:2016. From the results, the clean air delivery rate (CADR) can also be worked out. 

Portable air cleaners  

Portable air cleaners are generally used to purify the air in just a single room. Combining a fan and one or more of the cleaning devices discussed previously, they are a good option if the room that needs purification does not have access to a central HVAC system or forced air system. 

The performance of portable air cleaners is measured using the clean air delivery rate (CADR) or purified airflow rate. This measures the air purifier's delivery of contaminant-free air, measured in cubic meter per hour.  

Portable units may produce ozone as an unwanted and potentially harmful side effect. It’s vital to do your research before purchasing. You can view a full listing of Eurovent certified cleaners with their performances on our website. 

Which features are essential for Eurovent certification? 

Eurovent is Europe's industry association for indoor climate (HVAC), air conditioning and refrigeration, industrial heating, and air handling technologies. Eurovent Certita Certification (ECC) is Eurovent subunit dedicated to the certification of performances of HVAC products. 

ECC’s main missions is to develop and deliver certification programmes that cover air handling equipment, such as air purifiers. The organisation's criteria are designed to deliver ratings that allow consumers to make an educated and suitable purchase of air purification equipment.  

According to these criteria, products are assigned to Clean Air Efficiency Classes. Depending on performance, they are assigned a dedicated rating. In devising this rating, performance in the following areas is certified: 

  • Purified airflow rates for particles, gaseous pollutants, allergens, and microorganisms
  • Energy consumption
  • Recommended room area
  • Sound power levels

In conclusion, the best way to address the risk of indoor air pollutants is twofold. First, purchase a certified air purifier to manage indoor air pollutants. Secondly, put measures in place to control or fully eliminate the source of contamination and provide full ventilation from an outside source.