All Your Burning Questions About Air Purifiers For Home: Answered!

With all those doing the rounds on social media and WhatsApp, Indians are now considering investing in a good quality air purifier for home. But what makes a good air purifier worth buying and what features should you be looking at? We’ve got all the answers right here.

Why do I need an Air Purifier for home?

An air purifier, as the term states, is a tool used to purify the quality of air. People spend most of their lives indoors. Leading health agencies of the world estimate that, on average, than outdoor air. This includes common allergens like pollen, dust mites, pet dander, and mould spores but also exhaust emissions, smoke, VOCs, and other chemical vapours.

How do they work?

An air purifier works quite differently from a water purifier. There is no chemical treatment of air and the process depends on filtering air through a unit which will try and eliminate particulate matter that causes degradation of air quality. Depending on the quality of the air purifier, these can even eliminate particulate matter that is as small as 2.5 microns.

Even though air purifiers can’t help gaseous contamination, they are good at keeping a room free from dust, smoke and other vapour that can cause allergies and other health issues. Environmental bodies in the West have defined standards to determine the efficacy of air purifiers, relying broadly on the Clean Air Delivery Rate (CADR), which is the volume of clean air that a machine can deliver.

air purifier for home

Dust goes in, clean air comes out. A HEPA filter in action.

The EPA (Environmental Protection Agency) certifies a HEPA filter only if it can remove 99.97% of particles that are 0.3 micrometre in diameter, the CADR it decided on in the 1980s. In Europe, HEPA filters are graded from 9-17 depending on the percentage of particles they capture — from 85% to 99.999%. The classification takes into account the minimum zone of efficacy of the filter and the fall in pressure, and lays down the time after which the filter should be replaced.

What is a HEPA filter?

HEPA stands for High Efficiency Particulate Air. HEPA air purifiers were originally developed by the Atomic Energy Commission to capture radioactive dust particles. The HEPA air purifiers sold in the market today will not filter radioactive particles, but they will take care of common allergens. This makes them the key component of an air purifier, like the compressor is for an air conditioner. By definition, a HEPA filter is tested to certify that it can remove at least 99.97% of all particles 0.3 microns and larger.

Why the 0.3 micron size? This is the size of particle that scientists and testing have deemed to be the “most penetrating particle size”. Which means that of all particles, including those larger AND smaller, particles that are 0.3 microns have been shown to be the most difficult to trap, and thus, this is the standard by which HEPA filtration is measured.

What are activated carbon filters?

These filters are rarely used alone to purify the air, instead used along with other filters (like HEPA). Activated carbon/charcoal filters excel at absorbing odours and gases and neutralising smoke, chemicals, and fumes. When carbon is treated with oxygen, it opens up millions of review pores. There are so many of these tiny pores and fissures that one pound of activated carbon has a surface area of 60 to 150 acres. This huge surface area makes it ideal for adsorbing gases and odours, providing an enormous surface area for potential bonding with chemical/vapour molecules.

The larger the carbon filter, the more chemicals it absorbs and the longer it works. When it can adsorb no more chemical molecules, is when it has to be replaced. Impregnated carbon filters contain an additional chemical (a “chemisorbent”), that often either broadens the range of chemicals the carbon will filter or allows for more targeted filtration of a specific type or family of chemicals pollutants.

Do they consume excessive electricity?

Like all appliances, different air purifiers use different amounts of energy for operation. But unlike most appliances, an air purifier for home runs continuously, so you may want to consider your utility bill before buying an air purifier. (If only volts and amps are listed, simply multiply the two: volts x amps = watts.) Typical HEPA air purifiers can use anywhere from 50 watts on low to 200 watts on high.

Relax, air purifiers won’t hog all the electricity in your home

For comparison sake, a typical lamp uses about 60 watts, while a typical computer uses about 365 watts. Therefore, while its wise to consider energy usage, most air purifiers will not create a significant difference on your electricity bill.

So, how do I pick one?

Major brands have published studies stating that their products are able to filter out particulates, gases and bacteria. But while making a decision, it’s recommended that you look for air purifiers with HEPA filters and high CADR. Anyone with allergies should invest in a product with HEPA purifiers but since they tend to get choked with dust, always clean them regularly and replace them every few months.

Still not convinced?

An Air Purifier for home might not be for everyone but if you’ve been suffering due to the pollution, it makes sense to invest in one. If you still aren’t sure, then maybe and work your way upwards once you see some real benefits.

Breathe well, live long and prosper!

Thinker. Tinkerer. Writer. Editor. Many hats, one heart. Several roles, one goal. You get the picture. Right?


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