Growing pollution has undoubtly the biggest concern of modern world. This has led a significant portion of the urban population to face the slow, daily corruption of polluted air, creating a greater incidence of respiratory and lung diseases. You may think this is a major issue outdoors, especially on the motorways, but the danger also seeps into the home. Indoor air environments are often more polluted than outdoor air environments, especially in urban environments. Since a large part of our lives take place indoors, this is an especially ominous sign.
Don’t worry. This is a problem that has and can be solved. Through regular cleaning, vacuuming, design elements, and cross ventilation, you can reduce the airborne impurities and pollution within your walls. And to go a step further, you can always buy air purifiers.
An Introduction to Air Purifiers
Air purifiers, or air sanitizers, are compact machine units that convert polluted, impure air into purer air through a process of filtration. They are strictly for indoor use within a closed system, when the windows are shut so as to keep impure, outdoor air from undoing the purification process.
These units are usually portable, and can be placed anywhere in the house, depending on their design—there are tabletop, floor, and hanging purifier designs available on the market. Portable air purifiers can only be used for one room at a time, so it is advisable to get at least two of them, if your house is fairly large and inhabited round the clock. There are also whole home air purifiers but since those require installation by professionals in an already-made HVAC system — which is rare in the average Indian household — we will not be focusing on those. We will be focusing on the portable, smaller types of air purifiers that can be moved from room to room, as per your needs.
However, keep in mind that there are many indoor air-related problems you will need an air purifier to solve, and one type of purifier can’t solve all these problems. Certain purifiers will solve some problems, while being powerless to solve others. Indoor air solutions aren’t catch-all.
The Different Problems That Air Purifiers Solve
- If occupants have allergies triggered by microscopic allergens.
- If occupants have asthma triggered by microbes.
- If occupants have Multiple Chemical Sensitivities (MCS) caused by chemicals.
- To absorb bad odours.
- To filter out pet dander and fur.
- To filter out dust and dust mite allergens
- To filter out smoke, from the stove, cigarettes, and outside.
- To kill or filter out bacteria
- Off-gassing or outgassing from new manufactured materials, like soft plastics, furniture, paint, and emission of other volatile organic compounds (VOC).
- To remove mold spores
Types of Air Purifiers
There are several types of air purifiers in the market, usually based on the filter. Each type has its strengths and weaknesses in solving air-related problems, and you can find out about them here.
HEPA stands for High-Efficiency Particulate Air. These are a type of mechanical air purifier, and are among the best purifiers available. They mechanically pull impure air inside with a fan. Airborne particles, pollutants, and allergens are filtered out through a mat of tiny fibres, usually fibreglass. The ultrafine, microscopic impurities get stuck in the fibres, and the purer air is then passed out the other side, into the room.
The minimum size of impurities that HEPA filters can safely filter out is 0.3 microns. They can efficiently clean at least 99.9% of all the particles as small as 0.3 microns. The larger your HEPA filter mat, the more air you will be able to purify. Also, certain HEPA filters will be better than others—the HyperHEPA filters are better filters that purify even smaller particles, down to 0.003 microns. It is worth noting that the reliable certification label for any HEPA filter is “True HEPA Filter.” Other filters that use the label “HEPA-type” or “HEPA-like” are misleading, and can only capture particles as small as 2-5 microns.
HEPA filters have to be periodically changed due to accumulating all these impurities, usually after every 6 months to 1 year. Often, these products come with a pre-filter, so as to remove larger particles before they reach and clog the HEPA filter. These pre-filters are made of cotton, pleated paper, foam, non-woven polyester, or other fibres. Some have electrostatic properties. They need to be replaced regularly, every 3-6 months.
Since HEPA filters cannot filter out harmful gases, chemicals, and odours, it’s advisable to use it in combination with an activated carbon pre-filter inside. They remove odours, smokes, certain gases, and certain chemicals, by adsorption through activated carbon filter. They, too, have a lifespan of 3-6 months. Otherwise, check the manufacturer’s recommendations on replacement intervals for filters. It will depend on the air quality and frequency of usage.
UV Light Filters
This type of purifier is a mechanical one, that uses ultraviolet (UV) light inside to kill germs. However, they are not very effective as UV light needs a large exposure time period to kill germs and air moves too fast through the filter to do that effectively. These purifiers don’t have an actual filter in the physical sense, as they are only emitting UV light onto the intake air, before passing it out. Due to the presence of UV light, they release ozone which is harmful in larger quantities. Hence, people don’t generally use this as a standalone unit—they use it as a supplemental filtration process within HEPA or other filters.
Heat Sterilization Filters
This is another type of mechanical purifier that uses high temperatures to disinfect air off its organic particles, such as mold spores, dust mites, and bacteria. The air returns to room temperature before it is passed out of the purifier. Air is passed over an inner ceramic plate that heats up to nearly 400°C. It is based on convection and operates slowly. It is not effective against chemical vapors, smoke, and other inorganic particles.
Charged Media Filters
Charged Media Filters combine a particle filter along with an electrostatic charge filter to capture particles as small as 0.1 microns. They are very efficient in purifying air, but need to be replaced fairly regularly to ensure optimal performance.
Electric Air Purifiers
They are two types—Ion generation purifiers and Electrostatic precipitator. Ion generators emit negative ions into the air, forcing impurities to cling to nearby surfaces and the floor.
They may create dirty spots on these surfaces which need to be cleaned. Electrostatic precipitators function just like charged media filters but instead of using filters to capture particles, the particles precipitate and accumulate on the collector plates. These plates can be washed clean and do not need to be replaced. It doesn’t use a fan, hence, it isn’t noisy. It can be used in bedrooms overnight, without disturbing light sleepers.
Ozone Generating Purifiers
Ozone generators clean the air by producing ozone, which reacts with the pollutants to form less harmful compounds that then drop to the floor. They don’t use fans i.e. they are not a mechanical air purifier. So they do not need filters and sidestep the necessity to clean and replace filters. But they have been shown to produce more than the safe limit of ozone indoors, and this can be harmful to occupants.
Photocatalytic Oxidation Filters
It makes use of a titanium dioxide coated metal plate along with UV light to oxidize and physically break down chemicals during the filtration process. By doing so larger molecules break down into harmless carbon dioxide and water molecules.
Considerations for Choosing Air Purifier for Your Home:
There are a few important aspects to consider before choosing an air purifier for your home is
Speed & Airflow:
This can be measured in two ways.
- Air Change Per Hour (ACH): The number of times a purifier changes the whole volume of air of a room in an hour. The higher the number, the cleaner the air tends to be in the room. Use high ACH purifiers for occupants with allergies, asthma and other respiratory diseases. Check the manufacturer information on the same, before buying.
- Clean Air Delivery Rate (CADR): This is the measure of delivery of purified air at a purifier’s maximum speed setting. It pertains to the amount of airflow and how efficient it is at removing particles. It is measured in cubic feet per minute (CFM). The CADR is proportional to how fast an air purifier can purify. HEPA filters often achieve the highest CADR. CADR between 75-250 is a great choice, and anything under 60 is poor. Check this before buying, and correspond it to the room use.
Size of the Room:
Always consider the size of the room or rooms you are planning to purify. If you are purifying a large room, you will have to consider an air purifier with a higher coverage area. On the box or website, the manufacturer will recommend the coverage area (usually in square feet) that is suitable for the air purifier unit. Look for ones with higher CADR and ACH if your room is fairly large. Look for the opposite if you use a smaller room and want to save money.
Ion generators, ozone, and electrostatic filters emit their method in a 360 angle, so you will need a room with an open space, with place in the middle preferably. If you place these purifiers against a wall or table, then you will reduce its output. Mechanical air purifiers use a fan and have an inlet and outlet, so they, too, would need an open space to be placed in.
Most purifiers are used in bedrooms, since that is where the majority of the time is spent in the house. In such a case, you might want a quiet air purifier, such as an ionization or electrostatic one. Mechanical air purifiers like HEPA always have a fan, and that can get noisy based on the speed of the fan. In such a case, you might want a purifier with multiple fan speeds, so as to reduce and increase airflow and noise as per one’s preferences.
You might have areas of the house that are difficult to reach with the portable air purifier. In that case, you might want to buy one that has ducting options, where a duct can reach the elusive area you want to purify. There will be an inlet and outlet ducts available, along with duct ports.
Air purifiers, especially in heavily polluted cities, will need to be used 24×7. As such, they will be consuming energy and you might need to conserve money and reduce your electric bill. In such a case, look for Energy Star Rated purifiers. This is a reliable label that proves the purifier is frugal in terms of energy consumption.
- Air Quality Indicators: These are electronic indicators that notify users of the air quality indoors. These are very valuable for knowing how well the air purifier is working.
- Filter change indicators: Certain higher-end air purifiers notify users when their filters are clogged, and past their change date. A light or mobile app notifies them to change the filter.
- Multiple Fan Speeds: Most air purifiers have 2 fan speeds— high and low. The higher-end ones can have as much as 5, so as to make your life easier.
- Wi-Fi: Wireless internet capability allows purifiers to be controlled and analysed from afar, through mobile apps.
- Wheels and handles: These allow the purifier to be moved around from room to room easily.
Reliability of Brands
Obviously, it is preferable to buy from reputed brands with great products. There is not much regulation of air purifier standards in the global market, so many lesser known brands can sell faulty or misleading products. Check for official certificates and ratings. And research the brands who are well-known in this industry, to reduce losses. These include Blue Air, Airpura, Austin Air, Quest, IQAir, Oransi, Coway, Airfree, BISSELL, Envion, Honeywell, TruSens, and Whirlpool. Follow the guidelines given here, and stay within your budget, and you will surely make a great choice. Good luck!