Delhi smog: Things you should know before buying an air purifier
As air quality in the national capital region deteriorates to the “severe” category and your lungs protest, you need to know what to look for before buying an air purifier.health Updated: Nov 10, 2017 09:56 IST
The dense smog that envelops Delhi-NCR every winter prompts residents to invest in devices such as air purifiers that curb the level of pollutants indoors -- be it dust, pollen, chemicals and mould.
As air quality in the national capital region deteriorates to the “severe” category and your lungs protest, you need to know what to look for before buying an air purifier.
Barun Aggarwal, CEO of BreatheEasy, provider of indoor air purifying solutions, gives a checklist:
HEPA filter is a must
Check the specification of the air purifier to see whether it has a HEPA (high efficiency particulate air) filter. “There are many products in the market which say HEPA-like filters, people must avoid these. The HEPA filter clears out the small particulate matter (PM2.5 and less) that can go deep within the lungs and cause respiratory problems,” said Aggarwal.
Heavy activated charcoal
While buying an air purifier ensure that it has activated charcoal in it to remove harmful gasses as well as bad odours.
Check for a pre-filter
Buy air purifiers that have a pre-filter to remove the larger particulate matter. “In an air purifier that doesn’t have a pre-filter, even the large particulate matter present in the air would reach the HEPA filter and reduce its efficiency,” Aggarwal said.
Pre-filter can be easily cleaned or replaced, prolonging the life-span of the purifier.
High Clean Air Delivery Rate
The higher the Clean Air Delivery Rate (CADR), the more air gets purified. The number describes the purifier’s ability to remove all pollutants from specific amount of air.
Area to be purified
Usually manufacturers list the area the air purifier works best in square feet. “While buying a purifier, you have to halve the area and see whether it suits your need. This is because manufacturers test equipment in a sealed environment with the purifier running at high speed. These conditions are not possible in real life because running a purifier at full speed is noisy and home and offices have leaky windows and doors opening, which brings doown efficiency,” said Aggarwal.
Avoid purifiers with negative ions, photocatalytic oxidation, UV lights
Avoid air purifiers that have either of the three specifications as these can potentially release ozone as a by-product. “Ozone is harmful for the lungs and is known to lead to more incidents of asthma attacks and other respiratory problems,” Aggarwal said.
(A version of this article was first published in February 2017. It has been updated since)