Wearable air purifiers find takers, but experts sound caution: ‘Not effective outdoors’

Although not as widely adopted as masks, wearable air purifiers are gradually finding more takers in the Capital. Last year, senior Congress MP Shashi Tharoor, a long-time user of such devices, highlighted their cost-effectiveness and sleek design. Against this backdrop, it is worth examining how this technology works and whether it is truly feasible.

Globally, the Asia-Pacific region — driven by China and India — dominates the wearable air purifier market, accounting for at least 35% of sales. North America follows with 30%, while Europe holds around 25%, according to industry studies.

What are wearable air purifiers?

Wearable air purifiers are compact, portable devices designed to deliver cleaner air directly to the wearer’s breathing zone. They are available in two main forms: mask-type purifiers and compact devices worn around the neck. The latter are small, battery-operated units that release charged ions. These ions attach themselves to fine particulate matter (PM2.5 and smaller), increasing the particles’ mass and causing them to settle out of the air.

In essence, these devices aim to create a “personal clean air zone”—a bubble of purified air around the mouth and nose. By drawing in ambient air and pushing filtered or ionised air towards the breathing zone, they seek to reduce the concentration of inhaled pollutants and allergens.

Which models offer more protection?

The type of technology present in these devices is a crucial factor in determining its effectiveness. Among available models, those equipped with High-Efficiency Particulate Air (HEPA) filters can remove a substantial fraction of particulate pollutants and allergens, sometimes reducing exposure by 40% to 90% for particles like PM2.5, pollen, or dust mites in semi-enclosed or stable air conditions. By contrast, ioniser-based models generally deliver more modest results and may pose health risks due to ozone emissions.

Do they work in outdoor environments?

A December 2024 study at the National Aerosol Facility, IIT Kanpur, led by Professor Sachidanand Tripathi, tested wearable air purifiers in controlled indoor environments. The researchers recorded up to a 90% reduction in airborne particles within 30 minutes in a 35-cubic-foot chamber, and over 80% reduction within five minutes in a smaller 2.35-cubic-foot enclosed space.

“The study was conducted under a limited scope,” Professor Tripathi told The Indian Express. “Under the conditions we tested indoors, we found it does lead to removal of pollutants.”

However, he cautioned that outdoor environments — with constantly changing aerosol loads and wind movement — introduce “several complexities”, making these devices suitable strictly for enclosed spaces. “In a room environment, if the fan is off and ventilation is limited, the air is relatively quiescent… the device performs effectively,” he explained.

The report concluded that wearable purifiers are mainly effective in reducing airborne particles within “personal breathing space” under enclosed or low-ventilation indoor conditions.

Dr Nikhil Modi, Senior Consultant in Respiratory and Critical Care at Indraprastha Apollo Hospitals, echoed this view. “In highly turbulent or open outdoor settings, their effectiveness diminishes rapidly due to the constant mixing of polluted outdoor air with the small zone around the wearer,” he said.

The purifier evaluated in the study, developed by Atovio, works on variable anion technology, emitting millions of anions every second that attach to airborne particles, making them heavier and causing them to settle.

Can they match the protection offered by N95 Masks?

Experts caution against viewing wearable air purifiers as a solution to Delhi’s pollution crisis. Sunil Dahiya, lead analyst and founder of Envirocatalysts, an independent environmental research organisation, remarked: “Wearable air purifiers are merely an added cosmetic accessory that can spark conversations about poor air quality, but they are definitely not a solution. Even the reduction in exposure to pollutants is very limited.”

Most wearable devices cannot match the high level of protection offered by certified N95 masks, particularly against gases or in heavily polluted outdoor environments. “An N95 mask is a much better personal protection device than a wearable purifier,” Dahiya emphasised. “The real freedom from high pollution exposures will only be achieved by reducing emissions at source, not by forcing everyone to use gadgets to limit their individual exposure.”

Who should consider using them?

Wearable air purifiers can generally be used by most adults and older children, especially those with respiratory issues, allergies, or sensitivities to pollution and odours. Urban commuters, outdoor workers, and individuals in high-exposure occupations may also find them useful.

However, caution is advised for certain groups, including young children, pregnant women, and people with medical implants such as pacemakers. Ioniser-based models, in particular, raise safety concerns due to limited testing in these populations. For high-risk individuals, professional medical advice is strongly recommended before use.

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