How to select the best Air-purifier ?

How to select the best Air-purifier ?

Last weekend, the air-pollution levels in Delhi peaked to a three-year high. People in Delhi-NCR woke up to a Sunday morning with an overwhelming grey, opaque smog hung in the air and the city’s vast landscape having disappeared under its sweep. There are multiple reports of extremely poor AQI levels in most Indian cities, irrespective of the vehicular density. This air-pollution is quite harmful, especially for vulnerable population including children, old-age & people suffering from respiratory & related diseases. While, the solution to this humongous problem is beyond individual efforts and calls for society, government & corporates to work together. Air-purifier is a equipment that can offer you some relief. This post describes what essentially an air-purifier is and how one can select best ai-purifier or what things one should keep in mind while selecting an air-purifier.

What is an Air-Purifier ?

An air-purifier is device which removes contaminants from the air in a room to improve indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke. 

Most of the commercially available air-purifiers in market come with High-efficiency particulate arrestance (HEPA) filters designed to remove at least 99.97% of 0.3-micrometer particles. Additionally, the purifiers also have ultraviolet germicidal irradiation (UVGI) sterilize air from micro-organisms.

How does an Air-purifier work ?

What type of Pollutants can air-purifier remove ?

  • Pollens
  • Plant spores and fungi
  • Dust and dust mites
  • Pet dander and hair
  • Mold spores
  • Toxins from aerosol sprays and pesticides
  • Volatile Organic Compounds (VOCs) found in paint, varnishes, cleaning supplies, new carpet and building materials
  • Bacteria and viruses
  • Tobacco and wood smoke, and its smell,
  • Household odors from cooking, pets and chemical cleaners

How to select the appropriate Air-purifier ?

Selection of appropriate air-purifier depends on number of factors including:

Room Size:

Type of Filters:

  • Generally air purifiers use either of the below mentioned filters:
    • Composite filter
    • HEPA filter
  • You should go for HEPA filters – equipped Air-Purifier.


  • CADR stands for Clean Air Delivery Rate and signifies how quickly the air-purifier functions.
  • It calculates how many cubic feet of air the purifier can filter in one minute.
  • Air purifiers consist of three CADR numbers for dust, pollen and smoke.
  • Higher the CADR number, better the air filtration. Hence, If you have a larger operating space, consider going for and air purifier that has higher CADR rating.


  • ACH stands for Air Changes per Hour and signifies the number of times in an hour the purifier will clean the air completely.
  • Example a purifier with ACH of 4 will clean air of room 4 times in an hour. That is, in each 15 minutes it will perform, one cycle of cleaning the air of room.

Indoor Air-Quality Indicator

  • Few air-purifiers come with an Indoor Air-Quality Indicator, these indicators reflect the quality of air in real-time in your room.


  • One obvious thing to check is the product warranty. Other than this,
  • Air-purifiers need to replace filters from time to time. This cost has to be accounted. You can check prices of basic filters here.

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