Moving back to India after 15 years and with 2 young kids (one at 4 years age and the other only 10 months old) we realized very quickly that the air of Delhi was not good as both started developing wheezing and our younger one seemed to be worse than the older one. Having a building with the cleanest air of Delhi and a full laboratory to test air quality parameters at our disposal, I set about to test every air purifier I could get my hands on for our kids. The learnings from this were not only incredible, but scary. Most of the air purifiers we tested, ended up being “harmful” for lungs as they either emitted Ozone or they had negative ionizers that when accumulate in a closed space, will produce Ozone as a byproduct. Others has UV, PCO or other technologies that had too many questions around them! The few that did NOT emit Ozone were at varying degrees of efficiency. We found the “best” one and put that in our kids room. Five weeks later, the wheezing was gone.
We tested 36 different models of air purifiers from various manufacturers (AAF, Atlanta, Austin, Bionaire, BlueAir, Crusader, Daikin, DeLonghi, Eureka Forbes, Euromate, Honeywell, Hoover, Hosair, IQ Air, Kent, Panasonic, Phillips, PureAir, SANYO, SHARP).
We developed 15 parameters (airflow, PM reduction, cost, quality of filter, ozone production, etc.) and then did a user survey to determine how important some of these features are to a consumer. We gave each parameter a weight based on user preferences and then we tested for each parameter with each product.
What we realized that most of the products were designed for countries where air quality is much better than the air we had in New Delhi. And the manufacturer recommendations on room size, filter replacement, etc. were often way off for the environmental conditions in New Delhi.
The two most important criteria based on the high pollutant levels in New Delhi, turned out to be the airflow of the unit (CADR) and the total area and quality of the filter used. Hence, a lot of VERY expensive machines that ranked very highly on most independent review websites did NOT score very well in our tests, because the deep stack of filters caused a heavy pressure drop and the total amount of air coming out of the machines was not adequate to clean the high levels of pollutants in our environment.
We found an air purifier that did reasonably well on these 2 criteria, but had its own flaws. We discovered that this unit has a well sized, good quality true HEPA filter and the air flow is also very good. But the downside was that the HEPA filter was getting clogged very quickly as even the large particles were getting trapped by the HEPA filter.
So we customized the product to retrofit a pre-filter to the machine WITHOUT losing too much of the airflow. Now, we have a machine that has a good filter and airflow without the need to change the more expensive HEPA filter very often.
Click here to find out details on this machine and click here to find out details about pre-filter.
We have continued to test more air purifiers since and till date, with all the rigorous tests, we have shortlisted 3 brands that work well. Within these brands also, there are some models that are better than others. The brands are:
To view the shortlisted models of air purifiers, or to place an order, click here.