Air purifiers are a common household equipment nowadays. With the onset of winters in Northern States, the demand for air purifiers has increased. The fast-approaching festive season is also a reason why homeowners concerned by rising air pollution are rushing to buy air purifiers.
The air purifier is a unique product in the list of white goods available in the market. It does not promise to provide cooler air or bring down the ambient temperature, albeit it promises fresher air. While our ancestors might have scoffed at the idea, living in a metro city today is akin to smoking a pack of cigarettes daily. The average life expectancy of people living in Delhi NCR and other major urban centres is 2 to 3 years less than people living in relatively cleaner urban and rural hinterlands. So, the promise of clean air definitely has an appeal for people who are environmentally aware and know about health issues that are caused by indoor air pollution.
Now, there are several technologies in use today for indoor air filtration. However, the most effective and widely used technology is High-efficiency Particulate Arrestance air filtration. We know that’s a mouthful so we will be using the popular acronym, HEPA, from now on. So, let’s understand how HEPA air filters work.
High-Efficiency Particulate Arrestance (HEPA)
The simplest form of filtration is to use a material with holes that are big enough to trap some particles and small enough to let through others. That is how a normal sieve works. An air filter is also like a sieve that traps particles in the ambient air. But how do you catch particles that are floating in the air? Well, by making a very fine filter with holes small enough to let air through but trap everything else. That’s what we call a HEPA filter. It can trap almost 99.97% of the dust particles and polluting agents in the air. But there is a catch.
The holes in a HEPA filter are so small that they will simply get clogged by larger dust particles that get pulled in by the air purifier’s fan. Therefore, for a HEPA filter to run efficiently, a pre-filter is needed. The pre-filter is a simple sieve that stops the larger dirt particles and hair from reaching the HEPA filter but allow the microscopic matter to escape.
Thence comes the HEPA filter. It has a paper-like look. The material is folded in a zig-zag fashion and looks like a concertina. However, the mat is actually a form of dense fibre glass which cleans the incoming air using three very different mechanisms.
- Particles that travelling at high speeds because they are lighter, get trapped as they smash into the fibre wall.
- Particles at travelling at moderate speeds are snagged by the fibres in the material as they rush by the fibre wall.
- Lastly, slow moving, relatively heavier dust particles wander around the filter for a time before sticking to the filter walls.
Together, these mechanisms enable the high efficiency of indoor air filtration we experience with HEPA air filters.
Fun Fact: HEPA filters were originally developed for the Manhattan Project, to capture the dangerous, radioactive dust produced by nuclear fission. Today, these filters are widely used for making indoor air filtration systems for factories and workplaces where dust is produced as an operational by-product.
Types of HEPA Filters
With adoption for commercial and home use, the HEPA technology has witnesses some further bifurcation in terms of quality and use-cases.
True HEPA: A high-quality HEPA filter that can trap 99.97% of dust particles that are 0.3 microns in diameter. For comparisons sake, a human hair is about 50 to 150 microns in diameter. So, a true HEPA filter is effectively trapping particles several hundred time smaller than the width of a human hair.
HEPA Filters in Breathing Masks: The second grade of HEPA filters is used in pollution masks and respiratory equipment. These are often graded in 9 different types and have three levels of efficiency (95, 99 and 99.97) combined with three levels of filter degradation resistance (N, R, and P). The higher the quality, the longer the mask with HEPA filtration can be worn.
Things to Look for When Buying an Air Purifier
Well, it goes without saying that an air purifier with a true HEPA filter is the one you want for your home. It is the most effective at filtering particulate matter which is the term used for extremely small air pollutants. A genuine HEPA filter can remove particles rated between 2.5 to 10 microns in diameter. These particles include the sooty pollutants from vehicular emissions, household dust, pet dander, fur and hair. Moreover, a true HEPA filter is also more hygienic and resistant to degradation and can filter certain types of microbes, including viral and bacterial elements and mould spores.
The second thing to look for in a home air purifier is the addition of activated carbon filters. These filters provide an extra layer of protection by removing volatile organic compounds like formaldehyde and gaseous elements like carbon monoxide from the air filtered by the HEPA filter. Activated carbon also neutralises odours, providing relief from pollutants like second-hand smoke, off-gassing from plastics, and harmful fumes produced by paints and varnishes.
Air Purifiers for Home and Office
Now that you know what to look for in a home air filtration system, here is where you can look for it. Our air purifiers are rated for their high-efficiency and inclusion of patented HiSivTM activated carbon filters. Moreover, our tool-free mechanism and child-safe air purifier designs ensure convenience and safety during day-to-day household use.
Now you can check the complete range of our air purifiers online at www.honeywellconnection.com or at your favourite online shopping portals like Amazon.