What is the best air purifier to buy? This is a question that comes up a lot, especially from people in Delhi. Although the early days of lockdown to prevent the spread of coronavirus saw the air quality improve drastically, things have been inching back to normal, and particularly in North India, the levels of pollution are again highly dangerous. A number of factors go into this — from a return in electricity demand, to more vehicles coming back on the roads, and as an annual feature, stubble burning in farms in Punjab, which experts say is a huge contributor to the problem of air pollution. Although stopgap measures like restricting the number of cars on the roads, or banning fireworks will help somewhat, they won't be able to make a big difference either.
And that's why, if you can afford one, then having an air purifier is a must. However, this doesn't just apply to people living in Delhi (or the North Indian region) alone. In Mumbai, the air quality in the Colaba area is 800 (it should ideally be under 50) according to AQICN. On Breezo's data, it is 915 at the time of writing, and other areas like the airport are much better — but still ten times worse than the acceptable levels. According to the platform's visualisation, that's the equivalent of smoking five cigarettes. Bengaluru appears to be one of the best major cities in terms of air quality, with levels that are only three times higher than the acceptable.
And of course, the problem isn't just about the air outside the house — the air inside is no better. Not only are the pollutants from outside coming in, but because pollutants inside the house from cleaning sprays and perfumes, candles and cooking gas, and even dander from your pets or chemicals like varnish on your wooden furniture, are all entering the air you breathe.
So, it's clear that we need air purifiers, but what's the right one to pick? In this guide, we're going to explain how air purifiers work and what you need to know about them, so that you can make a more informed choice — but if you're looking for some suggestions instead, then just jump to the last section, called “Which air purifier should I buy?” to see our recommendations.
There isn't a definitive answer — we simply don't test enough air purifiers to be able to say “this is the one”, and from what we can tell, most people who are making similar recommendations are also actually looking at the same pool of products. Apart from the basic functions (which boil down to a fan and a filter) most air purifiers come with various extra features and you'll have to decide what is actually useful for you.
All the purifiers in the list are ones that I've personally tested, using an Air Quality Monitor (this one, if you're curious) to independently verify their effectiveness, and so that we're not reliant on the inbuilt air quality measurements. This has the additional advantage of allowing us to test the effective range of the air purifier — with the AQM, you can check the readings at various parts of a room to see how far away the air is actually getting cleaned.
|Air Purifiers in this Article
|Xiaomi Mi Air Purifier 3
|Philips AC 2887
|Blueair Blue 211
|Dyson Pure Cool Link
|Dyson Pure Hot+Cool
|Dyson Pure Humdify+Cool
Tejasvini Puri, at Blue Sky analytics (a Delhi-based company that analyses air quality) talked to Gadgets 360 about some of the data that the company has gathered this year, and explained that although pollution did significantly drop during the lockdown, this was not just because of fewer vehicles on the roads (as people had to stay home for social distancing) but also because of a decrease in the electricity requirements, as industrial units also had to go offline at the start of lockdown.
PM10 particles, which are connected to construction sites, burning crops, and pollen, had peaked around Diwali last year, and from late December continued to decline slowly until March, after which the levels dropped sharply and remained low until September, from when there's been a sharp rise. NOx particles, which are largely linked to vehicular pollution, dropped to almost zero in March, but from August, this has also been rising, as people have started to get back to work and more cars are on the roads again. PM2.5 particles, which cause smog, have been rising steadily across September and October, after a six-month period where the air was clear.
Dhariyash Rathod, CEO of Smart Air India, a company that makes DIY air purifier kits that are much more affordable than a typical air purifier, also warned that the winter is not going to continue to see clear skies. “Despite the COVID crisis and people working from home, Delhi has witnessed very poor air quality in the past few weeks. Factors such as crop stubble burning, industrial pollution, and low temperatures are some of the reasons for deteriorating air quality in Delhi,” he said.
The drop in power consumption and subsequent shutdowns of power plants led to some of the biggest gains in air quality, and as life returns to normal (and so does demand) this is turning around again, bringing the smog back to the city, Blue Sky's Puri said. Add to that stubble burning picking up again in September, and the problem is only getting worse.
“What we've seen across these readings suggests that crop burning and the power plants are the main causes for pollution in Delhi and the other areas in the region,” Puri said. “This means that the air quality is going to get worse again, unless major changes are made.” And although there are some measures coming in place such as smog towers, the volume of pollution is so great that unless you're standing right next to a tower you're not likely to see a real benefit, she pointed out.
Abhilasha Purwar, CEO of Blue Sky, wrote about this in a blog post and said, “As the world reopens again, it will fall upon us to reimagine its structure. Reimagine the priorities for the budget, policy, technology, and implementation. Re-demand clean air, lower emissions, aggressive climate action.”
So it's clear that you need to buy an air purifier. But buying an air purifier is complicated, as there are a huge number models to choose from, with a number of different features, and it's hard to quickly and easily make sense of the jargon. Some even argue that this is intentional — if there's enough confusion in the customer's mind, they might be more likely to stick to known brands, and expensive models, when something much simpler could do the job. More likely though, is the fact that brands all keep looking for some differentiation to stand out in the market, and in doing so, end up creating this confusing mess without even having to try.
However Rathod of Smart Air has some tips that customers can keep in mind.
“There are thousands of air purifier models to choose from, so how can you find the best air purifier that's right for you? First, ignore the marketing hype. First thing which one should look in an air purifier is to ignore the claims about proprietary technology that aren't backed up by the test data. Find third-party test data like AHAM to verify a purifier's effectiveness,” he said.
“Go straight to the numbers — instead of marketing hype, focus on the numbers. The most important numbers for an air purifier are the room size it covers (in sqft or m2) and its CADR rating. Room size means how big a room the purifier can cover (when running on its highest setting). CADR tells you how much clean air is coming out of the purifier. If you're looking for a quieter air purifier, choose one with a higher room size/CADR number and then run it on low,” he continued.
As Rathod pointed out, the core of a purifier is really just two parts; the filter and the fan. The design will determine what's most effective in sucking in air and clearing out the room, and while a HEPA filter is a standard to be followed, additional filters like a charcoal filter are used for trapping unwanted smells, toxic fumes, and other Volatile Organic Compounds (VOCs) and so you'll want to check about the different filters in a purifier before you purchase it.
CADR — Clean Air Delivery Rate is an important number to look at, as Rathod pointed out. But some companies don't use this figure. Dyson, the British company which is best known for its vacuum cleaners, entered the air purifier market a few years ago, and it argues that this figure isn't too useful for real world conditions. “CADR test is done in a small 12 square meter room, with the air purifier kept in the middle of the room, with a ceiling fan to spread the air around the room,” the company said in a mailed response, “The challenge however is that this isn't exactly representative of the real-world environment.”
So Dyson instead uses something it calls a POLAR test. As part of this test, the company explained, the air purifier in question is placed in one corner of the room, pretty much how you would probably keep it in your living room or bedroom. The pollutants are then added into the room from the other corner, which is perhaps the toughest test of strength for an air purifier. There are nine air quality sensors places in all corners of the room including one sensor in the centre, to understand the exact air quality in the different parts of the room at all times.
"Customers in India like to compare specs a lot," a Xiaomi representative told Gadgets 360 earlier, "but this is one product where I don't think that's actually a great idea. I think you should focus on how transparent the brand is being, like when it gives you indicators about clean air, so you actually know what the purifier is doing. Look at things like the cost of the filter, and how easy that is going to be to replace. Look for smart features, by which I don't just mean convenience, but smart like automatically adjusting the filter based on the air quality, and sending you an alert to change the filter."
Speaking to Gadgets 360 earlier, Girish Bapat, Director, West and South Asia for the Swedish company Blueair, stressed on the importance of a HEPA filter. "A HEPA filter will remove most of the PM 2.5, allergens and mites, from the air. It an also filter out smaller particles, like cigarette smoke," he added. "You should check the particle size that is being filtered, it should be 0.3 to 0.1 which catches even viruses that make people fall sick. But that doesn't remove bad odours and pollutants in gases. For that, activated carbon is best. Sulphur gases and carbon fumes from the outside, cooking releases gases, so a carbon filter is very important too."
“Finally, know that more expensive doesn't mean better. It seems logical, the phrase ‘you pay for what you get' exists for a reason, right? And who wouldn't want to pay more to protect their health? Unfortunately, the purifier world doesn't work like that. Turns out air purifiers are surprisingly simple – they're just fans and filters that can even be DIY-ed at home,” said Smart Air's Rathod.
So far, we've got an understanding of some of the causes of pollution, and why we need a purifier at all. CADR (or other measures that similarly give you and idea about the rate at which clean air comes from the purifier) are the main starting point to look for. A genuine HEPA filter is another important factor to look at. Further filters like a pre filter will help extend the life of the HEPA filter, and a charcoal filter will help with gases. So far this is simple enough.
How about purifiers that have additional features like displays showing the air quality, or ultraviolet light to kill viruses (specially for people who are worrying about COVID?) and other features like Internet connectivity and smartphone apps?
Let's talk UV first. Dyson points out that UV light uses radiation to destroy bacteria, viruses and mould. However, it does not remove dust, allergens or particles in the air. This means that for the normal pollution related issues, you don't need to buy a purifier that has this feature — but if you don't mind spending the extra money, it could have benefits. However, it's worth noting that for covid specifically, the likelihood of the virus simply hanging in the air in your home is pretty low. Companies like IQAir are doing this for hospitals, but at home it might not really make a big difference.
“When buying an air purifier, the consumer must check if the purification system is capable of removing small particles (0.0003 size microns), viruses and bacteria. It should provide quick cleaning for all sizes of rooms and have a real-time air quality assurance feature that can help you analyse the pollutant levels in the air,” said Dipanjan Chakraborty, Business Lead, Domestic Appliances, Philips Indian Subcontinent.
Some purifiers, such as the ones from Dyson's line, include humidifiers for dry conditions, and heaters for the winter. Having tried these, it's safe to say that they're extremely effective in those roles — but from a purification perspective, this doesn't make a difference. If you don't want to clutter your house with multiple devices to deal with dry air or cold weather along with pollution, this could be very handy, but these purifiers are also a lot more expensive than something basic like a Mi Air Purifier, so you're going to have to balance the cost against your needs.
Other features, like a digital display showing the air quality, sound nice in theory, but in practice don't really affect your usage. The best way to use an air purifier is the same way you use a water purifier — you keep it running at all times while at home. You wouldn't filter only some of the water in your home, and in much the same way, you won't be constantly checking the air quality and adjusting the purifier. Almost every purifier on the market has an auto mode which checks the particulate matter levels, and automatically adjusts the fan speed to compensate.
Smart apps that let you control the purifier whole away from home also sound nice, but in practice, you're not likely to use this feature often — these are fun gimmicks, and if you don't mind spending the extra money, by all means go for them, but they're not essential.
Actually — yes. We've mentioned this before, that the core of a purifier is a filter and a fan, and Smart Air started out by selling kits to put together your own purifier. Today, the brand sells its own air purifiers as well, priced at Rs. 8,499. We haven't tested this one yet, but it claims a CADR of 315cbm per hour, and it has a fantastic design.
The company also has a series called Ladakh, which is meant for larger spaces, like an entire home, a gym, a school, or spaces like hospital rooms. It has one of the highest CADR ratings for a standalone purifier, cleaning 890cbm per hour, with an effective range of 1,400 sqft, while the Ladakh Mini has a CADR of 585cbm per hour, and an effective range of 900 sqft.
However, the company still sells standalone HEPA filters too, for Rs. 3,550 — or if you like, you can buy some on Amazon, where they are even cheaper. Just make sure that you're buying a genuine HEPA filter, and strap it onto a fan to get started. Visit the Smart Air website to learn more about DIY air purifiers.
If you've made it this far, you should have an idea about how to choose an air purifier yourself. Look for a brand that's well known, so that it'll be easier to get servicing done when needed. Look for key information like the use of a genuine HEPA filter, the air delivery rate, and other features that matter to you. For a bigger room, you'll need a higher CADR, and for a small room, you don't need to spend so much money. But if you're not interested in wading through all the details and just want someone to help you figure out which air purifier to buy, here are some of my favourites, which I've personally tested.
One of the cheapest air purifiers in our list is the Xiaomi Mi Air Purifier 3. It's priced at approximately Rs. 10,000 on Amazon, but I've seen the price drop by a few hundred rupees during festive sales. Unlike the original Mi Air Purifier, which came with a “HEPA-like” filter, this one comes with a true HEPA filter and there's a touch display for the controls that also shows the AQI level, and a CADR of 380cbm per hour.
It's affordable and effective, and has a simple appealing design, which makes it a popular choice among many people. But if you're looking for a different brand, then at around the same price, the Philips AC1217 is another good option. Having used this one in Delhi, it's tested in some of the worst conditions. It's typically selling for just over Rs. 10,000, but frequently discounted as it is an older model. It's effective and fairly quiet too, with a CADR of 260cbm per hour. For bigger rooms though (around 300 to 400 sq ft) the Philips AC2887 is a better idea — it has a higher 333cbm per hour CADR, making it a good value for money buy.
For just a little more, we're still big fans of Blueair, and specifically the Blueair Blue 211 priced at just over Rs. 20,000. This purifier is small and stocky and looks great with a colourful cloth filter on top apart from the other filters. It doesn't have too many bells and whistles — you just turn it on and let it do its thing. But it's very effective despite its small size, with a CADR of 590cbm per hour. When tested in a large open room, this was the most effective purifier as seen with the AQM — it doesn't have Wi-Fi or a display or an app, but if you just want to switch it on and forget about it, this is a good pick.
Our last two picks are three Dyson air purifiers — the Dyson Pure Cool Link Air (review), priced at Rs. 29,900, the Dyson Pure Hot+Cool Air Purifier (review) priced at Rs. 55,900, and the Dyson Pure Humdify + Cool Air Purifier and Humdifier, also priced at Rs. 55,900.
Although Dyson doesn't agree with CADR as a measure, in our own testing we found these to be highly effective — the second most effective purifier we've tried, after the BlueAir. Aside from the air purification, these are premium products that are popular for their design, and they double up to fill secondary functions — whether cooling the room (which is fun but not that meaningful in most Indian cities), acting as a humidifier (which isn't as effective as a standalone humidifier that you can get for less than Rs. 5,000, but does the job well enough that you don't need to keep two devices in the room) or a room heater (which it does much more safely than a typical radiator or blower).
These purifiers come with all the bells and whistles, and the experience of owning one is definitely one that speaks to the premium positioning of these products. But if your main concern is air quality, then the cost of the newer devices especially might be a bridge too far for many people.