FcIf I say that there is more pollution indoors than outdoors, you will say that I am out of my mind. However, what I say is true.

Research conducted by the World Health Organization (WHO) proves that air inside our homes is 2.5 times more polluted than the outdoor air.

Air is the same everywhere. The only things that separate indoor and outdoor air are the walls and windows of the home. Hence, closing the windows can keep a majority of polluted outdoor air from entering the rooms.

In spite of that, you have to contend with natural ventilation that can bring in minute particles of polluted air (fewer than 25 microbes).

Major sources of Indoor Air Pollution

Compared to vehicular and industrial pollution outdoors, you have allergens, pollen, dust, etc. inside our homes.

Crop Burning

Having trees all around the house can certainly improve the amount of oxygen you get to breathe. At the same time, they bring an increased risk of pollution by the release of pollen.

This is one of the major sources of indoor pollution. In spite of having proper ventilation, they can still find their way into the homes.

You have dust to contend with. Your floors might look sparklingly clean, but you do have invisible particles of dust floating all over the place. This consists of mites, animal dander, outdoor minerals, and other minute particles that can trigger asthmatic and allergic reactions.

Another major source of indoor pollution comes from cooking, cleaning, and having indoor pets. The modern indoor decorations and furnishings can release gases and other volatile organic substances like cockroach and mosquito repellents.

The solution to the problem

Now that you have understood that you have a potentially dangerous solution on your hands, there is a need for finding out a solution. One way is to maintain the optimum humidity levels of the home at around 40 to 60%.

The biggest benefit of this exercise is that it makes the air comfortable to breathe and helps in maintaining the moisture levels of our skin. You ensure this by installing a high-quality air purifier/humidifier.

What are the aspects to look into when you decide to buy an air purifier for your home? This buying guide will take you through the entire process.

Air Purifier Buying Guide

There are different types of technologies to contend with. Let us look at them one by one.

Filter based

You have three types of filters in use in air purifiers.

Pre-filterActivated Carbon FilterHEPA Filter

This traps the bigger particles like dander, hair, dust.

Elimination of bad odor is the principal responsibility of this filter. It also takes care of gases like formaldehyde, toluene, and other volatile organic compounds like mosquito and insect repellents.

This filter removes the minutest of pollutants including bacteria and viruses.


Allergens and other airborne particles are positively charged. The process of ionization involves the production of negatively charged ions that attract these positively charged particles and cause them to fall to the ground. However, such filters release small amounts of Ozone that is dangerous to health.

This Is How Bad New Delhi's Air Pollution Is

Ozone Generators

You have some air purifiers that are in fact ozone generators. They produce Ozone, a harmful gas that can lead to worsening of asthmatic conditions, cause chest pains, and decrease immunity levels.

UV Filter

The pollutants have to pass through a UV sterilization chamber that results in the elimination of mould, viruses, and bacteria. However, you cannot use them in areas having a human presence because UV radiation is bad for health.

Photo Catalytic Oxidation

This process produces hydroxyl radicals capable of breaking down smaller particles, odours, and chemicals and converting them to either carbon dioxide or water vapour.

A word of caution here is that one should not for ozone generators masked as air purifiers. It is better to opt for a HEPA filter with the additional protection of Activated Carbon filters.

EXPLAINED: What is the Air Quality Index and how does it work?

CADR – Clean Air Delivery Rate

CADR is a measure of delivery of purified air by an air purifier at its maximum speed setting. It accounts for both the amount of airflow and particle removal efficiency. You should check out the CADR when you purchase an air purifier. Higher the CADR higher is the efficiency of the air purifier for a given room size.

Area Coverage

This equipment can be a heavy one thereby requiring adequate clearing space on all sides. You should factor in these conditions before purchasing one for your home.

The general recommendation is that you should opt for a model having a higher capacity than you need. This will enable you to operate the equipment at a lower setting thereby saving electricity and reducing noise levels.

The choice of the air purifier depends on the place where you install it. If you buy one for your bedroom, choose an air purifier that makes less noise to allow you to sleep peacefully.

In case you have one in your hall, you can opt for a purifier having variable settings. This would enable you to increase the settings when no one is in the hall to be disturbed by the noise levels.

Filter types

Filters are the most important ingredient of any air purifier.

A TRUE HEPA filter is the most recommended one for your house. They have the capacity to eliminate 99.97% of pollutants of the size of 0.02 microns.

HEPA Filter

You might come across many air purifiers stating they have HEPA-type, HEPA-Style, or HEPA-like filters. Naturally, they are not as effective as TRUE HEPA. It is invariable to have a quality washable Pre-filter to protect your HEPA and Activated Carbon filters from contamination thereby increasing their lifespan.

Indoor Air Quality Indicator:

Normally, in an air purifier, you have an indoor air quality indicator that changes color depending on the quality of the air.

This enables you to adjust the fan speeds accordingly. The modern-day purifiers have an automatic setting that allows the purifier to set the speeds automatically.

The latest ones in the market come with a numerical PM 2.5 display setting that helps you perceive how bad the air is.

Delhi chokes on air pollution

Customer Service:

Any filter requires change after 12 to 18 months. Hence, you should ensure easy availability of replacement spares. The after-sales service provided by the dealer is very important.


Remember that your air purifier is expensive equipment. Hence, having a longer warranty is vital to protect you from unnecessary manufacturing issues.

Individual requirements

One should note the following points about individual requirements while looking for air purifiers.

1 Asthmatic patients should opt for air purifiers having TRUE HEPA filters while avoiding Ozone based purifiers.

2 Air purifiers take care to eliminate a majority of allergens. However, the HEPA Filter technology is the one that ensures 100% elimination of allergens.

3 People living in construction areas must ensure to have a purifier having a strong pre-filter. They should change these filters frequently as well.

4 People living in industrial areas should opt for a purifier having the Activated Carbon filters to remove the obnoxious odours from the air.

5 People having pets at home should also opt for air purifiers as you have to contend with pet hair and dander.

6 People having lower immunity levels and those on dialysis and suffering from cancer should install air purifiers of good quality in their homes.

Inline Feedbacks
View all comments