Diwali is still a fortnight away. However, several regions in north India are witnessing thick smog due to worsening air quality. Although a huge issue every year, 2020 poses twin challenges — pollution and the novel coronavirus, a deadly contagion that causes COVID-19, a respiratory disease.

Also read: Air pollution linked to 15% of coronavirus deaths: Study

If the scenario feels scary and you’re looking to buy an air purifier to clean indoor air, but are confused over specifications, look no further.

Here are the things you should keep in mind while buying an air purifier:

HEPA filter

HEPA stands for ‘high-efficiency particulate air’ filter. These clear out the small particulate matter (PM2.5 and less) that can go deep within the lungs and cause respiratory problems, Hindustan Times reported.

You should, however, avoid products that say HEPA-like filters.

Activated charcoal

Ensure your air purifier has activated charcoal as it removes harmful gases and bad odour.

Clean Air Delivery Rate (CADR)

CADR determines the purifier’s ability to remove pollutants from a specific amount of air. It is either measured as cubic meter of air delivered in an hour or cubic foot of air delivered in a minute.

The higher the CADR number is, the better.

The Association of Home Appliance Manufacturers (AHAM) recommends the 2/3rd rule which means that air filters for a room should have a CADR greater than 2/3rd of the room area in sq ft.

Also read: 476,000 infants killed by air pollution worldwide in 2019, highest in India: Study

Area

Manufacturers mention the area the air purifier works best in. However, while buying, halve the area and see whether it suits your need, according to Hindustan Times.

This is because manufacturers test equipment in a sealed environment with the equipment running at high speed. However, such conditions are not possible in real life.

Negative ions, photocatalytic oxidation, UV light

Absolutely avoid those purifiers that have either of the three specifications as they can potentially release ozone as a by-product, that is known to lead to asthma attacks and other respiratory problems.

Energy rating

To save electricity and money, look out for purifiers energy star-rated.

A higher star rating would mean an efficient appliance, in terms of less electricity consumption.