Your Air Purifier Says 99% Clean. Is Your Indoor Air Actually Safe?

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You turn the air purifier on and watch the number on the display drop, and you let out a sigh of relief. The room looks cleaner, the air feels fresher, and the machine proudly tells you that it has removed 99% of pollutants. But there's a crucial question many of us fail to ask: 99% of what?

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Air purifiers can be very useful, especially in houses exposed to high levels of outdoor pollution. But they do not remove every contaminant that may be present indoors. It is important for respiratory health to know what your purifier can and cannot remove. We spoke to Dr Anjali R Nath, Pulmonologist, Department of Pulmonology & Chest Medicine, HOSMAT Hospital, who explained if your indoor air is safe.

What Do Air Purifiers Remove?

Most air purifiers (the ones most commonly used) that have high-efficiency particulate filters are designed primarily to catch particles.

"Among these are dust, pollen, pet dander, and fine particulate matter such as PM2.5, minuscule particles that can penetrate deep into the respiratory system. Filtration is thus particularly useful when outdoor pollution levels are high or when indoor activities create airborne particles," explained Dr Nath.

But there's a catch.

The efficiency quoted for a device is usually the efficiency under certain testing conditions and for certain particle sizes. That doesn't mean that 99% of everything in the room is gone.

The Pollutants Your Purifier Might Be Missing

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There are pollutants your purifier might not be removing. The indoor air quality is more complicated here.

Most air purifiers, especially those that primarily use particle filtration, fail to remove gaseous pollutants. These are volatile organic compounds, or VOCs.

"VOCs are emitted from paints, cleaning products, furniture and many common household products. For example, formaldehyde and benzene are VOCs that can be found indoors. Other products such as air fresheners, perfumes, aerosol sprays and other scented products may also contribute to indoor VOC levels. Cooking and combustion can also add gaseous pollutants to the home," added Dr Nath.

So, your purifier may be doing a great job at removing PM2.5, but if you are using multiple fragranced products in a closed room, the air may still be contaminated with gaseous pollutants.

"Some air purifiers use activated carbon or other gas-phase filters to adsorb certain VOCs. But their effectiveness depends on the type and amount of filter media, the pollutant, and how the device is used. No single purifier will guarantee the removal of all gaseous pollutants," explained Dr Nath.

Where Ventilation Comes In

One of the most basic principles of indoor air quality is the following: Filtration and ventilation do different jobs.

An air purifier will constantly filter pollutants out of the air that goes through its filter. Ventilation helps bring in cleaner air from outside and remove built-up pollutants from inside.

This is especially important when cooking, using cleaning products, painting, spraying perfumes or air fresheners, or otherwise releasing gases into the air. EPA guidance suggests increasing ventilation when products emitting VOCs are in use.

"Ventilation should be considered carefully when outdoor air pollution levels are high. Simply opening windows during a severe pollution episode is not always helpful. The idea is to take advantage of clean outdoor air when it's available and to reduce sources of pollution indoors," shared Dr Nath.

Treat Your Purifier As Part Of A Larger Strategy

A good indoor-air strategy is not just "air purifier versus ventilation." It is both an air purifier and a source of pollution reduction.

"If you are concerned about particulate pollution, use a properly sized purifier with the correct particle filter. Maintain filters cleanly and change them as recommended by the manufacturer. Don't assume every purifier will handle VOCs. If gases and odours are a concern, look for a device with an appropriate activated-carbon or other gas-removal system," advised Dr Nath.

And most importantly, don't get a false sense of security from a reassuring number on a purifier's display.

Bottomline

Dr Nath concluded, "Clean-looking air is not always clean. Your purifier may be doing a good job. But good indoor air depends on what you add to the room and what you let off into it, and whether you have a place for that air to go."

Disclaimer: The information provided in this article is for general informational and educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or a qualified healthcare provider with any questions you may have regarding a medical condition.