Winter is coming. No, this is not another discussion about Game of Thrones, but a different context. With winter about to set in, air quality in different parts of India will take a major hit. This is especially the case post Diwali celebrations. In fact, going by recent trends, owning an air purifier is no longer a luxury, but a necessity. After all, indoor air quality tends to be far worse than the air outside.

Invisible to the naked eye, the air in our homes can contain a range of pollutants. These include dust, pollen, tobacco smoke, pet allergens, dust mite allergens, Formaldehyde, Benzene, and more. It is a similar case with our water supply, and hence water purifiers have long become a standard appliance in all our homes. It is high time an air purifier becomes one too. But therein lies a problem – how do you select the right air purifier? Brands use a lot of marketable terms while trying to sell you their appliances, and more often than not it just adds to the confusion. So, we are here to demystify these terms. We also narrow it down to two major aspects that need to be kept in mind when choosing the right air purifier.

Air cleaning standards: Quality vs Quantity

Brands rely on one metric to prove the efficiency of their product – ‘Clean Air Delivery Rate (CADR)’. This basically takes into consideration the room size and how quickly the purifier can clean the air in that room. In other words, the higher the CADR number, the more clean air it can throw into the room. Brands like Xiaomi, Philips, Blueair and others rely on this metric. Other companies like UK-based Dyson however claim that CADR tests are obsolete, and rely on their in-house tests. Dyson’s test is called ‘POLAR’, which it says is more in tune with modern homes, particularly in India.

In a CADR test, an air purifier is placed in the center of a 12 square meter room and run for 20 minutes. One air quality sensor in the room then monitors the change in the pollution levels. After this test, the purifier is given a CADR rating.

The POLAR test however is a tad different. It is conducted in a bigger 27 square meter room, and the purifier is kept in one corner instead of the center. The pollutants are then added into the room from the opposite corner. Unlike the CADR test, Dyson keeps the ceiling fan off, and uses nine air quality sensors to monitor air quality in different parts of the room. On paper, the POLAR test comes across as a more stringent indicator of an air purifier’s efficiency. It focuses more on the quality of the air than the quantity of air being pushed out of the purifier.

Filtration: What goes in shouldn’t come out

Just like water purifiers, the filters in an air purifier play the most important role. The purifier sucks in the air from the room, passes it through different filters, and then pushes out clean air. Purifiers use a range of filters including Pre-Filters, High Efficiency Particulate Air (HEPA), and Activated Carbon to name a few.

For example, Xiaomi’s Mi Air Purifier 2S features a 360 degree triple-layer filter containing a primary filter, a Toray H11-grade EPA filter, and an activated carbon filter. Dyson’s air purifiers too feature a 360 degree glass HEPA filter along with activated carbon filter. The sealed unit can trap air pollution particles as small as 0.1 micron, which is 100 times smaller than a human hair. In comparison, most other HEPA filters can trap particles up to 0.3 micron. What’s more, the sealed filter doesn’t let any pollutant escape.

Price vs Function

Air purification standards and filtration systems then are two of the most important aspects that need to be kept in mind when choosing an air purifier. Other aspects like design and added features are just a matter of choice. But in a country like India, another aspect that plays a major role is price. Most of our buying decisions are made based on the pricing.

But for a product like an air purifier, one can’t simply rely on the price tag when making a buying decision. After all we are talking about air pollution, which can silently have life-altering consequences. This in turn can lead to huge hospital bills.

These days buyers are spoilt for choice, and air purifiers are available for prices ranging from Rs 6,000 to Rs 60,000. They all have their own set of pros and cons. But when it comes to the growing air pollution, it makes a whole lot of sense to take the long-term view and can go for the best possible purification money can buy.