Laboratory test
The laboratory sets up the CADR measurements. Photo: Anna Sigge
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Testfakta Research has conducted a comparative laboratory test of air purifiers for larger rooms on behalf of the Swedish manufacturer Blueair. The purpose of the test is to compare the performance of a representative and comparable selection of air purifiers on the European market.
The laboratory test was conducted by RISE (Research Institutes of Sweden). The test report is based on official requirements and guidelines and was drawn up in consultation with the laboratories involved.
The sample was chosen by Testfakta Research and covers models from the biggest brands in the European market. In terms of capacity, the sample represents purifiers with a declared CADR1 of over 350 cubic metres per hour, equating to a room of more than 70 square metres2.
With all the air purifiers in the sample, a mechanical fan draws the contaminated air through various types of filter which remove the particles from the air. Some products also have other purifying technologies such as ionising and a carbon filter.
The following air purifiers were tested:
All the models are current and the sample is representative of the offering on the British, German, Polish, Dutch and Nordic markets.
Check of the 13 different air purifiers on their arrival at the laboratory. Photo: Anna Sigge
Measurements at 37 dB, or the nearest level below 37 dB:
The laboratory sets up the sound measurements. Photo: Anna Sigge
B. Measurements at max power:
The results from the sound measurements are analysed. Photo: Anna Sigge
C. User friendliness
The air purifier’s settings are assessed. Photo: Anna Sigge
The air purifier’s capacity to purify air was tested according to ANSI/AHAM AC-1-2019 and Nordtest method NT VVS 106. The test measures the air purifier’s capacity to eliminate various types of particles (dust, pollen and small particles) from the air in a room. The cleaning capacity is stated as the Clean Air Delivery Rate (CADR), which shows the air purifier’s capacity expressed in cubic metres of clean air per hour.
The laboratory sets up the CADR measurements. Photo: Anna Sigge
How many square metres the air purifier is able to clean depends on the cleaning capacity (CADR), tied to how many times an hour the room’s volume of air is processed. According to Asthma Allergy Nordic, an air purifier in a bedroom should process the air in the room twice an hour. A bedroom of 25 square metres with a ceiling height of 2.4 metres has a volume of 60 cubic metres. In order to process this amount of the air, the air cleaning capacity (CADR) should, in this case, be at least 120 cubic metres per hour. If you want the air in the room to be processed three, four or five times an hour (as some manufacturers and retailers recommend), the air purifier needs a corresponding increase in capacity.
The sound level is an important factor, since the air purifier is often used to clean the air in a bedroom. According to Asthma Allergy Nordic’s guidelines, the air purifier’s cleaning capacity should be considered in relation to the noise it makes. The association recommends that the sound level in a bedroom should not exceed 30 dB(A), which is in line with WHO’s limit for sleep-disturbing background noise.
The laboratory sets up the sound measurements. Photo: Anna Sigge
In the test, the performance of each air purifier was measured at 37 dB(LWA) and on full power. Before the measurements were taken, the sound level was measured on all power settings to find the power level that produced 37 dB or the nearest level just below that. The power level was adjusted on the air purifier’s control panel or via the appliance’s app. Measurement of the sound level was performed in a controlled laboratory environment, following the international standard ISO 3741:2010.
The measured level of 37 dB equates to around 30 dB at a distance of two metres from the air purifier, which is considered a reasonable distance in a normal-sized bedroom. This assumption is highly dependent on how the room is shaped and furnished, but can be considered reasonable in the majority of typical bedrooms.
Most of the air purifiers have relatively low energy consumption (measured in watts (W) of electricity), but since they are intended to run more or less continuously, this figure remains important. The energy use was measured at the setting that produced 37 dB and on maximum power.
The assessment of user friendliness includes filter replacement, settings and controls, and displays and menus. The assessment was carried out by experts at the laboratory.
Some air purifiers clean the air using ordinary filters and ionising. Ionising involves the particles in the air being given a negative charge and then sticking to a positively charged metal plate inside the air purifier. If an ionising air purifier charges not only the particles but also the air itself, this forms ozone. Ozone is a health hazard over a certain threshold. The current threshold value for ozone (EU guidelines) is 0.055 ppm (parts per million). The laboratory measured the difference in ozone levels between the input and exhaust air from the various air purifiers. None of the air purifiers tested emitted ozone above the current EU recommendation (0.055 ppm).
The measurement results from the test have been interpreted and graded in consultation with the laboratory. The grading uses a 10-point scale, where 10 is the best. A grade of less than 6 is only given if the performance is poor or worse than one might reasonably expect for this type of product.
The grades from the different elements of the test have been combined to give an overall grade, using the following weighting:
Measurements at 37 dB, or the nearest level below 37 dB: 45%
Measurements at max power: 45%
User friendliness: 10%
