- If you live one of the most polluted cities in the world, namely- Delhi, Patna, Gwalior, Ahmedabad, Firozabad, Amritsar, Kanpur, Agra and Ludhiana. Don’t think I wrote most polluted cities in the world by mistake. It is a fact unfortunately! Other cities like Bangalore, Kolkata and Chennai too aren’t far behind when it comes to pollution.
- If your home/office is located in the midst of the city surrounded by vehicles or if its close to a construction site, factory or quarry.
- If any of your family members are pregnant or asthmatic or allergic to dust, pollen, smoke etc.
- If you have a pet.
The skeptic in you might still be thinking, “ Isn’t this like living in a bubble, which could ultimately take a toll on my tolerance and immunity to the outdoor pollution?” Well, let’s look at it from another perspective. Don’t you take vacation to refresh yourself and become energized? An air purifier does just that. After a day in traffic and city pollution, an air purifier helps you breath fresher air and re-energize yourself. Remember, majority of us spend at least 12 hours a day at our home and indoor air can be two to five times dirtier than outdoors.
Air Purifier & Ashthma
Even though a study by New England Journal of Medicine in 2004 showed that asthmatic patients had an overall better feeling living in homes with air purifiers, it is unfortunately not a definitive solution for all asthma patients. Environmental protection Agency (EPA) studies have shown that many of the air pollutants that cause asthma are less than 0.3 micron in size and they are not filtered using air purifiers. Also, portable air purifiers work best only in the room in which they are located. So, they must be placed in the rooms where the asthmatic patient occupies most of his/her time. Even so, residential air purifiers reduce the airborne particulates by around 80%- which is much better than nothing at all.
Does this mean an air purifier is the ultimate solution to all pollution woes?
Unfortunately no. As I mentioned earlier, air purifier reduces airborne particulates by around 80% only. It is excellent for filtering dust, smoke from candles, stove and pollen, and also reduces mold and fungal growth. It is particularly useful during winter when particulate matter less than 2.5 mg (PM2.5) increases. PM2.5 is said to penetrate deeply into the lung, irritate and corrode the alveolar wall, and consequently impair lung function.
But it not quite effective at filtering volatile organic compounds (VOC) from adhesives, paints, and cleaning products, and other types of gaseous pollutants. Though certain brands claim that they filter VOC, experts suggest that there is no filter that sieves all types of gaseous pollutants, as they are all of different particulate nature.
Factors To Consider While Buying An Air Purifier
I believe the above information would have helped you decide whether you need an air purifier or not.
Now, lets try to understand how to choose the right air purifier.
First and foremost, you have to consider the room size, number and types of filter used, CADR and air change rate. The rest of the factors are not as important as this. Below we explain each in detail.
Perhaps the most important factor that you have to consider is the size of the room where you intend to use it. For optimal efficiency and quietness, experts suggest buying a large unit (compared to room size) and running it on lower speed rather than cranking up a smaller unit.
The efficacy of the air purifier depends on a large extent to the number and type of filter used in it. Filters mainly used are HEPA filter, activated carbon filter, AC filter, anti-bacterial filter, ionizer etc. An air purifier may not have all these filters. But more the better and it SHOULD have a HEPA filter.
CADR(clean air delivery rate) measures the volume of air filtered by the purifier. It is measured in cubic feet per minute. Association of Home Appliance manufacturers state that assuming the height of a room to be 8ft, the CADR of an air purifier used should be higher than or equal to its square foot area divided by 1.55. So, for a room of 300 square feet, the CADR of air purifier used should be 193(300/1.55) or higher. But, most air purifiers in India have a much lower CADR compared to the area it is cited to be suitable for.
Air Change Per Hour( ACH)
The air change rate implies how many times the air in a particular environment is filtered an hour. To calculate this, we multiply the CADR by 60 to give the cubic foot clean air delivery rate per hour. Then, we have to divide it by the cubic foot space of a room (square foot x ceiling height) Ceiling height of typical home is around 10 ft. The end result will give the air change rate. Here is an example.
Suppose the CADR is 300m3/hr, then per hour, it changes 18,000 cubic foot of air. Suppose the room size is 500 sqft, then the cubic foot space of the room is 500 (sq.ft) x10(height)=5000. So, the air change rate is 18,000/5000=3.6. The American Association of Heating, Refrigerating and Air Conditioning Engineers suggest a minimum ACH of 4 for allergy and asthma sufferers. Unfortunately, many of the air purifiers in India have ACH rating between 2-4. So, you may have to use these air purifiers in rooms of lesser area than manufacturer's recommendation.
Check out our CADR calculator
Whether you are buying online or from a nearby store, ensure that they keep filters in stock. For the same reason, it is best to buy air purifiers from reputed brands like Panasonic, Philips, Kenstar, Eureka Forbes etc. as you can be sure of spares availability and servicing, which is not the case with fly by night operators who import from China and sell cheap.
Air purifiers come with a recurring maintenance cost. Its filters have to be changed frequently. The main filter has to be changed yearly, while the carbon filter has to be changed every three months. So, when you look at the price tag, factor in the yearly filter replacement cost as well.
Noise level of the air purifier is an important factor as it is mainly used in bedroom where most people especially babies need a silent environment to sleep.
Unless you can afford to buy multiple units, you may often want to move the air purifier from the living room to the bedroom when you go to sleep. Hence, opt for something that has handle and is lighter and easy to move.
And finally Brand Reputation
You know how some of the Chinese phones market themselves with features that come almost at par with an iPhone, but within less than 6 months, it just breaks down. That is precisely the reason why brand reputation is an important factor while buying not just air purifiers, but almost every home appliances and electronic gadgets. When you are spending Rs. 10-20k for an air purifier, it is always better to pay an extra Rs.1-2k for an air purifier from a reputed brand rather than buying from any of those sellers who dump cheap Chinese products in the market without offering any after sale service or warranty.
We just took a look at the important functionalities; now let us consider the important features to look for in an air purifier.
Number of Filters
As mentioned earlier, higher the number of filters better the air purification. Below is a general guideline on must have filters for different types of users.
- Allergy/ Asthma Patients- HEPA filter (avoid ionizers that emit ozone)
- Living near construction site/area with heavy traffic- Pre-filter, HEPA filter and activated charcoal filter
- Living with pets or areas with bad odour- Activated Charcoal filter and HEPA filter.
- People with compromised immunity- HEPA with anti-bacterial filter and Humidifier.
Fan Speed Adjuster
This helps to adjust the speed to suit different sized rooms and different pollution level. Certain models like Philips have mechanism to monitor the pollution level and automatically adjust the fan speed.
The performance of an air purifier depends on filter. Ensure that your purifier has a filter change indicator which alerts when its time for a filter change.
Child Proof System
Children love playing with buttons. A child proof mechanism ensures that the settings are not changed when kids play with it. Also ensure that the device doesn’t topple easily.
Though once you adjust the settings, you won’t have to keep changing them, it is always good to have an air purifier with remote control.
If you are living in a place that has dry climate, then, it is advisable to buy an air purifier with in-built humidifier. Its especially beneficial in homes with babies as it promotes better sleep, reduces infection (as bacteria and virus cannot travel in moist air easily) and keeps sinuses moist and comfortable. However, ensure that you pour filtered water in to the water reservoir as contaminated water could easily spread diseases.
Read our list of best air purifiers in India
Just like your water filter, air purifier also needs regular maintenance for optimal performance. Here are a few tips that might help.
- Preferably buy an air purifier with servicing indicator so that you are alerted to change the filters as and when needed.
- Clean washable pre-filters regularly, and make sure it is completely dry before you put it back.
- Ensure that the air purifier is not kept in a crammed space between furniture and wall. For optimal performance, the purifier needs enough space for taking in and releasing air.
- Just like how you use your air conditioner, close all windows and doors before you switch on the air purifier so that it is not over-burdened unnecessarily.
- Keep the area around the purifier clean so that it can work on filtering the allergens rather than the dust around the air purifier.
- Turn off the air purifier when you are dusting the room or if there is any carpentry work, as filters will get clogged very quickly.
- An interesting review we read gave a useful tip on how to check whether the purifier is actually working. The reviewer suggests putting incense stick behind the purifier to check how much of it is soaked by the purifier. Also, using a flash light from torch or mobile, you can see the dust particles being sucked in and air without dust being released out.
- In case the air purifier starts emitting odour, remove the activated carbon filter and HEPA filter and keep it in the sun for sanitising it.
Other Tips To Make Indoor Air Cleaner
- · Do not smoke indoors.
- Clean your home with vacuum cleaner home regularly.
- Use exhaust fans in bathroom and electric chimney in kitchen.
- Store cleaning liquids, chemicals, pesticides etc in a closed space away from the living area.
- Ensure proper ventilation.
- If possible, avoid using rugs and carpets.
- Grow air purifying indoor plants.