A Complete Guide to Air Pollution: PM2.5 Levels, Air Purifiers & More

7 min readOct 17, 2017

Last year the country witnessed it’s worst ever smog. The toxic air in the capital was actually compared to a gas chamber by many. 300 micrograms per cubic meter is considered ‘Hazardous’ on the Air Quality Index. Delhi was at 600 in November 2016, right after Diwali. That’s more than 60 times the level considered safe by the World Health Organisation. A combination of firecrackers, burning of crop, vehicular and construction pollution caused this deadly smog.

This year, in the face of the firecracker ban in Delhi, it may appear that things may be different. However, TOI reported last month that many farmer organisations, have threatened to burn large swathes of land yet again.Vehicles will ply, construction dust has been on the rise in all metropolises making air toxic is all these cities. Also, the enforcement of the firecracker ban is weak at best. Air inside and outside is likely to be unfit to breathe yet again.

AQI or Air Quality Index recorded in the month of October is already over 100 in not just Delhi, but many other cities. So how do you dodge this sticky situation?

Find Out How Polluted Your City Is

If you stay in Delhi, Mumbai, Pune, Kolkata, Chennai, Hyderabad, make sure you check the pollution levels in your city regularly. Air classified as Unhealthy by WHO has been noted almost throughout the year. Here are the two sources we recommend for finding out pollution levels in your city:

1. The World Air Quality Index project is a social enterprise project that provides a unified Air Quality information for the whole world. You can find your city’s pollution level there as well.

2. Accuweather app gives AQI for selected cities along with customised weather forecasts. For instance, if you have allergies, asthma, migraine, the app will tell you if the weather is beneficial for you that day.

If the AQI of your city is over 100, you are breathing air that can cause serious health issues. Here’s a chart to find out whether the air in your city is clean.

Needless to say that indoor air is as affected by pollution as outdoor air. Infact indoor air is sometimes worsened by allergens, pet dander, construction dust etc which act as carriers of particulate matter.
The effects of inhaling particulate matter that have been widely studied in humans and animals include asthma, lung cancer, respiratory diseases, cardiovascular disease, premature delivery, birth defects, low birth weight.

Who Needs An Air Purifier

1. People living in cities with an AQI > 100 ppm
Even if you have no history of respiratory diseases, it is important to exercise precaution if pollution levels in your city are unhealthy. Choose air purifiers that have a HEPA filter that removes particulate matter like PM 2.5 and PM 10 which can settle in the bronchi and lungs and cause health problems.

2. People with Asthma & Respiratory diseases
Air pollution exacerbates asthma. People suffering from asthma are advised by doctors, to not only limit physical activity outdoors, but have an air purifier running in the room as often as possible. Air purifiers filter out irritants like pollen, dust, mould, toxic gases and particulate matter which worsen conditions of asthma.

3. People with Pets
As such, pet dander is not harmful to human beings. But allergens like pollen, mould spores, dust mites attach themselves to the pet dander and cause allergies. Air Purifiers with Pre-Filters significantly reduce the amount of these allergens in your house.

4. Moms and Babies
If you plan on starting or expanding a family, you may need to be careful with the air you breathe. Multiple studies have determined air pollution contributes to lower fertility rates in men and women. In a study by The Stockholm Environment Institute (SEI) nearly three million babies are born prematurely each year because of air pollution.

How To Choose An Air Purifier: Specs & Fine Print

There are tens of air purifiers out there selling some different or the other. The specs may seem daunting and confusing with every company positioning their products as the best, but its important to consider the fine print, because lets face it, air purifier don’t come cheap.

Why are air purifiers expensive?
The starting price for any decent purifier is Rs 10,000. The HEPA filter which traps the micro particles like PM2.5 is the reason for this steep pricing. Air purifier without a HEPA filter is as good as an air conditioner — not worth it.

So here are the 5 most important things you need to consider in an air purifier

1. Filters : Pre-Filter, Carbon Filter & HEPA
HEPA or High efficiency particulate air (HEPA), originally called high-efficiency particulate absorber is the most important part of an air purifier. HEPA filters out the smallest of pollution particles like PM2.5 and 10 which cause the most damage in the human body as they are not naturally filtered out by the nose. Note however, a HEPA filter in isolation does not last very long. It should be accompanied by a minimum of a pre-filter so that load of filtering out big particles like dust and dander is not on the HEPA. Choose a purifier that has at least 2 filters to support the HEPA

2. CADR or Clean Air Delivery Rate
The higher the CADR, the better. At minimum it should be 100. CADR determines the rate at which air is cleaned inside the room. With a high CADR purifier, more air in your room will be cleaner at a point of time.

3. Ionizer — Good or Bad?
Many air purifier companies emphasize the benefits of an ionizer, crediting it with ‘mood lifting’ air. However, ionizers come with a byproduct, ozone. Ozone proves to be harmful especially for those with asthma. Some companies will not disclose clearly whether or not they have ozone. Do not settle for lack of information, and email the company if you are unsure of whether or not their product releases ozone. Definitely do not go for an air purifier that does not categorically mention ‘No Ozone’.

4. Noise
Ones less than 50 db should be fine to use at night when you sleep.

5. Filter Change Indicator
Without an indicator, it is hard to determine when the filter needs a change or cleaning. Choose one that comes with an indicator preferably.

Which Air Purifier to Buy

We analysed 20 different air purifiers from top 10 brands that sell in India. Out of these we handpicked 15 products from 7 different brands after going over hundreds of product reviews and separating genuine from paid reviews. We selected the best products suited to homes with different needs:

1. People with allergies & asthma
2. Homes with kids
3. Homes with pets
4. Quiet Air Purifiers

WHY
BlueAir is a pioneer in air purifiers. A Swedish company, they lay emphasis on not just the specs of their products but also on design and sustainability. The Blue Air Pure has the highest covered area from the 20 products we analysed and an unparalleled CADR at 594 m3/h, much higher than any other air purifier available in the Indian market. It has no ozone, so it’s perfect for people with asthma. It is also Energy efficient, made from 100% recyclable materials and has no chemical additives.

Amazon Price: Rs 22,800

Flipkart Price: Rs 22,699

Value For Money Purifiers

If you need a secondary purifier or one for a smaller room, there are many options under Rs 10,000. Check them out here

Outdoor exertion was strictly prohibited to everyone after the Great Smog of Delhi last year. But if you’re a runner, we feel your pain. One cannot just quit going for the daily run. Running and any other outdoor workout requires you to consume more oxygen than when your body is at rest. Naturally you end up breathing more polluted air than otherwise. To keep yourself healthy, it’s hence very important to wear a face mask with the N99 certification which is the only mask type that can filter out particulate matter (PM2.5)

See our N99 Pollution Mask Collection here