An air purifier has become somewhat of a household necessity in recent years. With air pollution in Delhi and neighbouring areas on the rise, it is imperative to take all measures necessary to keep the air at home clean. For that, you need an air purifier that suits your needs. But do you know which air purifier is best for you? Not all air purifiers are made equal, but that doesn’t mean that you need the most expensive one. Find out which air purifier is best for Delhi and for you with this comprehensive guide.

First, find out what to look for in an air purifier. Here are the things which you should be looking at when buying an air purifier for your home.

Image Source

1. Clean air delivery rate

The CADR, or clean air delivery rate, indicates the level of purified air produced by the air purifier. A higher CADR means a higher filtration capacity. You will find the CADR of air purifiers mentioned in the product specifications when you’re buying online. This number is generally mentioned in cubic metres per hour. Some manufacturers, like Dyson, are now using another, more accurate filtration test which makes CADR testing redundant. According to Dyson, CADR testing may not be accurate for a regular home and is done in a small area and for a short duration. Dyson uses the newer, more advanced POLAR test to measure filtration capacity.

2. Room size

This is imperative to know before you buy an air purifier. The larger the room, the stronger your air purifier has to be. If your room is small, you can opt for a smaller, hence cheaper, air purifier. But if you use an air purifier with a low CADR for a large room, it won’t make any difference to the air quality. The ideal room size for a particular air purifier is mentioned in its specifications. If you can, choose an air purifier meant for a room larger than the one you want to put it in, so that even at its lowest or quietest setting, it is still effective.

3. Air changes per hour

ACH, or air changes per hour, is literally the number of times the air purifier cleans the air in the room every hour. If you’re living in Delhi, with its toxic levels of smog, you need an air purifier with a minimum ACH of 4. This means that the air in the room is cleaned completely every 15 minutes. You may not always find this metric mentioned in the product specifications of air purifiers, but it’s easy to calculate. All you need to know is the purifier’s CADR and the size of the room in which it will be used.

How to calculate ACH rating of air purifiers

Convert the CADR, which will be in cubic metres per hour, into CFM or cubic feet per minute by multiplying the figure by 0.588. So, for example, if the CADR is 300 cubic metres per hour, the CADR in CFM will be 300 x 0.588. Multiply the result by 60 to get the volume of air changed per hour.

To find out the ACH rating of your air purifier, you need to now calculate the room volume. For this, find out the square feet of your room. Multiply that by the height of the room. For example, if your room is 300 sq ft and the height of the room is 8 feet, the room volume is 300 x 8.

The ACH rating of your air purifier will be volume of air changed per hour divided by room volume. According to this example, the ACH rating will be 10,584/2,400 = 4.41.

4. Type of filter

Most air purifiers have two types of filters – composite and HEPA (High Efficiency Particulate Air) composite. When you’re buying an air purifier, you should choose one with a HEPA filter for the simple reason that it’s more efficient and cost-effective. HEPA filters need to be changed every 9-12 months while normal composite filters need to be replaced every 3-6 months. HEPA filters also remove about 99.97 per cent of pollutants in the air, which is significantly higher than composite filters.

5. Cost of replacing filters

When you’re choosing an air purifier for your home, you should also check the prices of replacement filters. Filters of good air purifiers need to be changed every 9-12 months on average. So, you have to consider if you are willing to bear this annual cost of maintenance.

6. Air quality indicator

Most air purifiers come with an air quality indicator. Some have numeric displays while others have a colour display to indicate how clean or polluted the air in the room is. Air purifiers with numeric displays are generally preferred because you can then know the exact AQI of your home. Some air purifiers also have an auto setting which detects the air quality in the room and adjusts its settings automatically. The latest air purifiers also have mobile app integration so that you can control the air purifier remotely and keep a check on the exact air quality of your home.

The best air purifiers for Delhi

1. Dyson Purifier Cool formaldehyde Air Purifier (Advanced Technology), TP09

Get it here 

Price: INR 45,899

CADR: Not applicable, since Dyson uses the more advanced POLAR test to determine an air purifier’s strength.

Room size: Claims to work for all room sizes

Type of filter: HEPA H13 filter with a layer of activated carbon

Buy this because: It captures 99.95% of particles as small as 0.1 microns, the catalytic filter continuously traps and breaks down formaldehyde into water and CO2, filter life of 12 months, integrated with Dyson app which offers remote functioning, Wi-Fi enabled.

2. Honeywell Air Touch U2 Air Purifier

Get it here 

Price: INR 27,996

CADR: 650 cubic metres per hour

Room size: 1007.5 sq ft

Type of filter: HEPA H13 filter with activated carbon and anti-bacterial features

Buy this because: This air purifier also has a humidifier and child lock button, Wi-Fi enabled with real-time information on air quality and filter health, 3,000 hours of filter life.

3. AGARO Imperial Air Purifier 

Get it here 

Price: INR 14,999

CADR: 320 cubic metres per hour

Room size: 400 sq ft

Type of filter: Pre Filter, Cold Catalyst Filter, Activated Carbon Filter, Anti- Bacterial Filter, Green True HEPA Filter H14, UV Sterilization and Anion

Buy this because: The air purifier protects with 360-degree indoor air purification and removes 99.99% of airborne Pollutants, Smoke, Pet Hair, Bacteria, viruses and Micro Allergens

4. Coway Professional Air Purifier

Get it here 

Price: INR 12,900

CADR: Not available

Room size: 355 sq. feet

Type of filter: Green True HEPA Filter

Buy this because: Traps Oil Mist, Smoke and food Odor. Removes 99.99% of pollutants in just 2 minutes.

5. Philips Air Purifier-Series 3000 AC3059/65 With Wi-Fi

Get it here 

Price: INR 27,798

CADR: 400 cubic metres per hour

Room size: 517 sq ft

Type of filter: 3 filters (pre-filter, activated carbon, and NanoProtect True HEPA extra thick)

Buy this because: Removes 99.97% airborne pollutants as small as 0.003 microns, in the higher ranges of CADR and room size, app integration, tested for H1N1 virus, and filter change indicator.

Have you figured out which air purifier is best for you?

The products in this article have been carefully curated by the team after research. We may earn a commission on any purchase through this page.

Related: How To Combat Air Pollution In Delhi: Products To Help You Through This Toxic Weather