By Paul Dawson
We are living in the indoor generation, we are breathing in more pollutants indoors as we are spending majority of our time behind closed doors. Indoor pollution can come from outside when we open the windows or doors, but it can also be produced from everyday activities in our home, some of the sources include particles and gases from burning incense and cooking, dust build up over time on surfaces and bedding, and VOCs from furniture.
How do you select a good air purifier?
A good air purifier should cover the three elements of air purification: i) intelligent sensing ii) efficient filtration and iii) powerful projection. To purify an entire room properly an air purifier must sense pollution events automatically; capture particles and pollutants such as PM 2.5, PM10, PM 0.1 and harmful gases such as VOCs, formaldehyde and NO2 (Nitrogen dioxide) and project cleaner air to every corner of the room for even room purification.
What is the CADR score?
CADR was first introduced in 1980s, which stands for Clean Air Delivery Rate. This test measures the clean air volume that a purifier can provide in fixed amount time, and it is a measurement of speed. It doesn’t measure filtration quality or focus on how well a purifier captures smaller particle sizes. In real homes, filtration quality matters. If particles aren’t captured the first time, they are released back into the room. An air purifier with a high CADR rating does not necessarily imply that it is doing a better job of purifying your room properly; it may in fact be throwing a lot of the pollutants back into the air in your home- when particles travel at high speed through the filter, it can bypass the filter and go back into the room. And also, it might not be projecting clean air around the whole room.
Why is there a need for a new test method for air purifiers?
Each day we can breathe in between 9,000-11,000 litres of air and over 70 per cent of these breaths take place behind closed doors. With an increasing amount of pollution both indoors and outdoors, more and more people are interested in using air purifiers for a breath of fresh air, yet the existing measurements don’t truly reflect how purifiers work in real world environment. Backed by extensive in home research, we go beyond the CADR test which others use, and created new POLAR test which we believe it better reflects real home usage.
The problem with air pollution is that most of the time it is odourless and colourless. With our naked eyes, it is difficult to tell whether we need to turn on or turn off the air purifiers, a good purifier should do the thinking for us intelligently and automatically.
The CADR test has no measurement on intelligence or whether a machine delivers uniform cleaning in a larger family room. The test is conducted for 20 minutes in a compact chamber of just 11.8m2 (127 sq ft) in size, with an added fan to circulate the air (to ensure the air is mixed) and only one sensor to measure air quality. This setup is not representative of a larger living room environment in India. In addition, during pollution peaks in winter months, no ceiling fans are used to help circulate the air thereby creating a bubble of clean air just around some of the conventional air purifiers.
What is POLAR test and how is it different?
POLAR test lab is based on a larger room size of 27m2 (290 sq ft), with no added fan as we don’t use fans in peak pollution winter season in India. The air purifier is placed in corner of the room which replicates how it is used in real homes and pollution is pumped in the other corner. The test uses eight sensors in the corners of the room and one sensor in the centre, detecting particles of indoor air pollution that are 300 times narrower than a human hair. All machines are tested using their automatic pollution detection function as most consumers are not able to detect air pollution and just want to set their machine to automatically deal with any issues. The new testing method assesses the ability of machines to remove harmful particles and gases, the uniformity of the cleaning performance delivered around the whole room, and airflow projection. It starts when the machine thinks the room is polluted, and ends when the machine thinks it is clean. Analyzing the data across all nine sensors lets Dyson engineers ensure that our air purifiers are engineered for proper purification including efficient filtration and air projection, not simply for coverage time.
Dyson is actively engaged with Bureau of Indian Standards which is currently looking industry experts for their knowledge and expertise in this area, and we also consult with an external advisory board of respiratory specialists, to help guide our product development.
Who is adopting POLAR test and why?
China is the world’s largest and most sophisticated purifier market, its leading purifier test agency – China Household Electric Appliance Research Institute (CHEARI) has worked in conjunction with Dyson engineers to incorporate POLAR test method into an association standard. Experts at CHEARI have constructed a 27m2 test chamber in Beijing to better reflect real average home sizes of Chinese consumers. They recognise the need for intelligent machines and uniformity of cleaning performance and it’s exciting to be leading this technology change. We welcome other manufacturers to enter into this new category.
Paul Dawson is vice-president (Health and Beauty) at Dyson