What are the real performances of indoor air purifiers?


Indoor air pollution is now a real public health concern. Besides ventilation, the use of air purifiers is a solution often considered to improve indoor air quality by reducing pollution through the trapping or destruction of pollutants. The information provided by manufacturers praise and attest to a very high efficiency. What is it really about?

 Stiftung Warentest is a German foundation equivalent to the French UFC-Que choisir and whose mission is to provide consumers with objective information about the products they buy, by carrying out laboratory tests.

Both institutions are members of the International Consumer Research and Testing (ICRT).
Stiftung Warentest has been in existence since 1964, carries out comparative tests and is renowned for its neutrality. Its influence on the choices of German consumers is recognized.

Among the purifiers studied, half a dozen are available in France.

The tests carried out by Stiftung Warentest focused on the elimination capacity of 3 types of pollutants that are very common in the indoor environment of homes: cigarette smoke, formaldehyde and pollens.

How effective are air purifiers at removing pollen?

Pollen is made up of fine particles. The various manufacturers announced an elimination rate of allergens and PM 0.1 (ultra fine particles) of more than 99% and treatment surfaces of up to 106 m², but laboratory tests have not validated these claims.

The devices fared best with pollen, removing on average 90% of the pollen. However, it must be taken into account that this is not an "in-situ" study and therefore in reality things do not happen this way.

First of all, the study was done on a 16m² room and moreover, 2 million pollen particles were used, which is an enormous quantity.

The results show that the purifiers tested removed between 83% (Dyson) and 95% (Philips, Soehnle and Rowenta) of the pollen.

Knowing that it only takes a few particles to cause an allergic reaction in a pollen-sensitive person. For Stiftung Warentest, these results are still insufficient to protect allergic people effectively against air pollution by pollen.

How effective are air purifiers at removing cigarette smoke?

Cigarette smoke is composed of fine particles and more than 3000 chemical substances. Tobacco smoke is classified as a proven human carcinogen by the WHO (Group 1 carcinogens).

As far as cigarette smoke is concerned, the performance is far below what consumer equipment manufacturers claim!

For example, the Dyson model is a poor performer because it manages to eliminate at best 90% of the smoke in a room of only 7 m². The Philips, Soehnle and Rowenta models fare better with treated areas between 19m² and 23m².

The laboratory reports that the air purifiers were new at the start of the experiments and therefore at the top of their capabilities. Their ageing was evaluated with cigarette smoke and the results are indisputable: when the tests were continued over a longer period of time, the performance of the devices was significantly reduced.

"When the tests lasted longer, performance collapsed".

The German foundation adds that the filters must be changed very regularly, if only to obtain these results. The price of the replacement filters (from 39€ to 140€) makes the regular use of these devices almost prohibitively expensive.

How effective air purifiers are at removing formaldehyde.

Formaldehyde is a volatile organic compound (VOC) present in anyone's home. It is gaseous at room temperature and comes mainly from furniture, paints and household products. Formaldehyde is recognized as a proven human carcinogen by the WHO (Group 1 carcinogens) and its research is classified as a priority by the health authorities. It is irritating to the respiratory tract and contributes to the development of asthma and allergies.

The results of air purifiers for the elimination of formaldehyde are catastrophic compared to the performance expected and indicated by manufacturers. Indeed, while the devices in question announce an "elimination of formaldehyde thanks to their activated carbon filters", the performances are at best 45% (Soehnle) and go down to 11% (De Longhi).

The laboratory concludes that these devices are not very effective or even impotent to reduce chemical pollution by formaldehyde in a home.

Icing on the cake, Stiftung Warentest points out that many of these devices are connected to applications and that these transmit information that does not seem relevant to the accomplishment of their mission.

Should we believe the air purifier manufacturers?

After reading this test, when you visit the various sites of the devices in question, you cannot help but be surprised by the difference between what is advertised and what the tests of an independent laboratory reveal.

"There is a real difference between the test results and the performance announced by the manufacturers! »

Some brands also opt for an artistic blur when they advertise that a particular device is suitable for a medium-sized room, which means nothing but may reassure the consumer.

All of them advertise performances in terms of treated surface and filtration efficiency that we do not know how they were obtained when we know the results of these tests by Stiftung Warentest.

Finally, in the light of this survey, it is also important to ask questions about the methods used in research centers or "independent" certification bodies to test and evaluate the performance of these devices.

In addition to the manufacturers' communication praising the very high efficiency of indoor air purifiers, it is very difficult to obtain clear and precise technical information on the results of the performance tests they have carried out to qualify the efficiency of their product. These data are unfortunately not public.

"Consumers should not take the manufacturers' word for the performance of air purifiers".

UFC-Que choisir concludes that regular ventilation (2 times 10 minutes per day) and a reduction of pollutant emission sources allows a sustainable and lower cost improvement of indoor air quality rather than using these consumer appliances.

It is important to note that even if the performances are not up to par, or even very disappointing, air purifiers can still eliminate some of the air pollution. Manufacturers still have a lot of work to do to propose efficient air purifiers to consumers.

According to ANSES, only technologies based on HEPA filtration and activated carbon are recognized for their efficiency. Other technologies such as photocatalysis, ozone, plasma and ionization still have to prove their efficiency. Indeed, some technologies can generate pollutants in the indoor air instead of eliminating them!

 Only a laboratory analysis can identify indoor air pollutants with certainty and accurately measure the level of ambient pollution. These measurements allow you to know which pollutants are at risk in your indoor environment and to help you identify and eliminate the sources in order to sustainably improve indoor air quality.

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