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Posted at: Nov 11, 2017, 2:15 AM; last updated: Nov 11, 2017, 2:15 AM (IST)

Technology to the rescue

Jagvir Goyal

Besides the poisons of outside air flowing into your home, there are several materials used in the construction as well as in interiors that can  deteriorate indoor air quality (IAQ).  The awareness about air pollution due to stubble burning and vehicular emissions has led to the popularity of air purifiers. This year, there has been a spurt in the sale of air purifiers and every industrial house is adding unique features to these. Almost every big manufacturer in electronics items business is now producing air purifiers. This is advantageous for the consumer who can make a careful choice as per his requirement at competitive rates due to competition in the market.

How to choose a purifier 

Basic features of an air purifier are: a set of filters and fans to draw in and push out air. Here are some tips to choose a right filter:

Level of dust & smoke filtration

PM 10 and PM 2.5 are two popular terms related to Particulate Matter. Air purifiers fitted with HEPA filters are most effective in drawing Particulate Matter from the air. HEPA filters means high efficiency particulate air filters. These filters can draw more than 99 per cent of the particulates from the air. So, while buying an air purifier, look for the one fitted with HEPA filters.

Check for VOCs & gas filtration

Volatile Organic Compounds or VOCs are emitted from certain solids and liquids used in homes. Chemicals used in paints, varnishes and wax emit VOCs. Prolonged exposure to these can cause liver and kidney disorders, irritation in eyes and skin rashes. Gas pollutants cause shortness of breath, lung disorders, skin, eyes and throat irritation. 

Activated carbon filters can remove these gases. For removal of VOCs, Activated Carbon Filters have an extra chemical to trap and absorb the VOCs. Thus, look for a purifier fitted with an activated carbon filter suitable to remove VOCs also.

Efficiency in removing germs and bacteria 

While some air purifiers are fitted with anti-bacterial and germicidal filters and use UV rays to remove bacteria and germs from air, other air purifiers have HEPA filters especially treated with special agents that kill germs and bacteria in the air when the air passes through these filters. One should prefer having treated HEPA filter air purifiers. In case you have some pets, then the germ quotient of the indoor air may be higher. In such cases, ensure that the air purifier is capable of removing germs also in addition to the air pollutants.

Avoid ozone-producing purifiers

Ozone is a pollutant that causes respiratory disorders and lowers resistance to pneumonia and colds. Ensure that the air purifier selected by you doesn’t produce ozone. Check it from the dealer. If the purifier is fitted with an ion generator or ‘Electrostatic Precipitator’, then double check against ozone generation. 

Prefer pre-filter

If indoor air has heavy particulate matter then a purifier fitted with a pre-filter should be chosen. Pre-filters remove heavy particles from the air before passing air to other filters. These are washable (easy to clean) too.

Check for CADR

CADR means clean air delivery rate. Prefer an air purifier having CADR of 300 cubic meters or more.

Air changing efficiency

ACH means Air Change per Hour. An air purifier should be able to change room air with cleaned air at least four times in an hour.

BEE stars and energy efficiency

Choose an energy-efficient air purifier that doesn’t consume more than 100 watts per hour. However, the size of a room will decide the size of air purifier and for bigger rooms, electricity consumption may be a little more.

Maintenance aspects

Check that the frequency of cleaning of air filters and replacement of air filters in the air purifier is not frequent. While the interval of cleaning of filters depends on the level of air pollution, air purifier shouldn’t demand frequent replacement of air filters.

Smart features

While sticking to the basic requirements, one may also look for smart features. These include Air Quality Monitor which shows a red indicator if air needs purification. Another feature is Filter Replacement indicator that tells you that it’s time to replace the filters. Child lock, timer and sleep mode are other features. 

Check that the air purifier is silent type and doesn't produce more than 35 Db sound. You may look for remote control operation. PM2.5 display feature is provided in some purifiers. App based controlling has also been introduced.

The litmus test

On technical grounds, one may look for Indoor Air Quality (IAQ) Test. This test is now available in many cities like Delhi, NCR at a cost less than Rs 1000. This test involves the use of air quality meters by professionals to check air quality and determine the presence of Particulate Matter PM 2.5, harmful and toxic gases like carbon monoxide, nitrogen oxide and hydrogen sulphide in the air. Proper test report along with permissible range of each gas or item is given to you to decide whether to equip your house with an air purifier or not.


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