How to Choose the best Air Purifier

With air pollution touching new highs in Delhi and PM2.5 (Particulate matter less than 2.5 microns in size that can penetrate the lungs and cause damage ) levels almost at hazardous levels and normal surgical masks being useless against pollution;getting an air purifier at your home and office is no more a luxury or a fad .

Indoor pollutants are generally the ones that cause more harm since that is where we spend the chunk of our time. Read more about indoor pollution here.

Air purifiers are devices that clean the indoor air by removing suspended impurities such as dust particles, pollen, smoke and other airborne allergens. They help in providing less contaminated air, though many companies also claim that their purifiers reduce allergic reactions and asthma attacks. Air purifiers cost anywhere between INR 5,000 to INR 95,000.

Common Contaminants in the Indoor air

Pollen - (Average size 5-100 microns) - Having a green cover near your house is great for photography and brochures but God forbid if you are allergic to pollen or have too many indoor plants then you might need to consider an air purifier that reduces the pollen levels in the air .

Dust and dust mites – (Average size 0.5-50 microns) – Every house has dust and indoor dust particularly houses dust mites that are known allergens.

Pet Dander - (Average size 0.5-100 microns) – If you have a pawed friend or a winged companion and frequently suffer from allergies, you might need to consider an air purifier to get rid of pet dander and mites.

Molds - (Average size 2-20 microns) - Molds and fungus usually thrive in damp and dark places.

Smoke and VOC – Even if you are not a smoker, kitchen fumes and chemical odors from floor cleaners, deodorants ,stationary etc. can cause breathlessness and you might need to consider this while buying a purifier.

Bacteria and Virus – (0.35-10 microns) - These are omnipresent.

 Points to Remember when buying an Air Purifier

 Coverage area – You need to consider the size of your room or office to select a purifier just like an air conditioner.While selecting do consider the area of the space that needs to be purified .Most affordable room purifiers cover an area of 200-350 sq feet but if you need a purifier for a larger area then you shall need to choose your air  purifier accordingly .

       Filter Type - It is important to consider the kind of filtration your office or home   will need before   zeroing on one product .

1.Activated carbon Filter- Activated Carbon filters have small absorbent pores that chemically react to pollutants as they pass through the filter. effective at clearing smoke, odors, chemicals and even gases from the air, rarely used as stand-alone filters , mostly used in combination with other filters.

2.HEPA Filters -HEPA (High Efficiency Particulate Air or high-efficiency particulate arresting) filters work by pulling or pushing the air through a filter screen that catches these contaminants. A HEPA filter can trap 99.97% of all household airborne particles as small as 0.3 microns in size and 95% of minute particles down to 0.1 micron. HEPA air filters are the most recommended and useful for removing dust, pollen, mold and spores, though they are not very effective in removing VOC, smoke, odors and bacteria.

3.Ionizer Filters – Its a device that uses high voltage to ionize or electrically charge air molecules. Once a particle is charged, it will be attracted to anything with the opposite charge. Two metal plates within the purifier are charged (one negative, one positive) to attract these particles. Also, particles in the air will be drawn to each other if they have opposite charges. Once attracted to each other these particles clump together, get heavier and eventually they settle out of the air. They are very quiet compared to most HEPA machines. There are two major subdivisions: the fan less ionizer and fan-based ionizer. Fan less ionizer is noiseless and use little power, but are less efficient at air purification. Fan-based ionizers clean and distribute air much faster. Ozone may be produced in minimal quantities. The Ionizing filter effectively removes dust, pollen smoke and bacteria.

    4. Photo Catalyst Oxidation Filter – It uses short-wave ultraviolet light (UVC),    commonly used for sterilization, to energize the catalyst (usually titanium       dioxide (TiO2) and oxidize bacteria and viruses, effective on VOCs.

       Portability – Room filters can be fixed to the wall or can be portable .Choose as per your requirement.

Clean Air delivery rate ( CADR) – It determines how well the ambient air has been purified, if the purification process is very slow then the purifier is not going to help much . A CADR rate of 300 MCH is considered  good enough .

       Energy usage - While most units do not consume much energy in terms of wattage ,it does not harm to do a comparative check .

    Noise levels  - Some units are prone to make more noise which may be disturbing so this needs to be factored in .Some manufacturers specify and some do not specify the decibel levels.

    Display to show Air Quality index (AQI ) - This warns about when it is time to change the filters .

  

    Here is a comparison of some of the affordable and effective purifiers in the market :