Worn All Day. Zero Ozone Detected. 24 Hours of Testing Confirmed It.

TL;DR

• Some ion-based purifiers emit ozone as a by-product. IIT Kanpur tested the Atovio Pebble for 24 hours continuously in a sealed 1 ft x 1 ft x 1 ft chamber (28.3 litres).

• The sealed chamber was deliberately chosen because any ozone generated would accumulate rapidly with nowhere to disperse.

• Ozone concentrations stayed between 1.8 and 2.8 ppb throughout, with and without the Pebble running.

• No measurable increase in ozone was detected after the device was activated (IIT Kanpur Ozone Report).

• CARB limit: 50 ppb. WHO guideline: 60 ppb for 8-hour exposure. OSHA: below 100 ppb.

• Maximum ozone measured across the entire 24-hour test: 2.8 ppb.

• Measurement instrument sensitivity: 0.01 ppb. The Atovio Pebble is fully compliant with CARB, WHO, and US EPA ozone emission standards.

Why Ozone Safety Is Especially Important for a Wearable Device

A room purifier sits across the room. A wearable air purifier sits at your chest, a few centimetres from your nose and mouth, for hours at a time. That proximity means any emission, even at a level too low to smell or notice, would be concentrated directly in your personal breathing zone across extended wear.

Some designs that use ion-based technology produce ozone as an unintended by-product of the ionization process. At ground level, ozone is a harmful air pollutant. Prolonged exposure can cause coughing, throat irritation, and reduced lung function. Long-term effects include chronic bronchitis and irreversible lung damage. So the question of whether a portable wearable purifier emits ozone is a genuine safety concern, not a technical footnote.

The National Aerosol Facility at IIT Kanpur tested the Atovio Pebble for exactly this.

Why the CARB, WHO, and EPA Limits Exist

The California Air Resources Board (CARB), the World Health Organization (WHO), and the US Environmental Protection Agency (EPA) all set specific ozone limits for consumer devices because ionization-based products vary significantly in their ozone output. A device that reduces one type of air pollution while generating another is not actually protecting the people using it.

The internationally recognized thresholds are: CARB at 50 ppb, WHO at 60 ppb for 8-hour exposure, and OSHA at below 100 ppb for workplace settings.

How IIT Kanpur Designed the Test

The National Aerosol Facility designed the test to be deliberately conservative, meaning any ozone the device produced would be detected. The chamber was a sealed enclosure measuring 1 ft x 1 ft x 1 ft, with an internal volume of 28.3 litres. In such a small, fully sealed space, any ozone generated would accumulate rapidly with no ventilation to disperse it.

The Atovio Pebble was operated continuously for 24 hours under controlled conditions. Ozone concentrations were recorded at regular intervals using a calibrated monitor with sensitivity of 0.01 ppb, capable of detecting even the smallest trace. Background ozone was recorded before device activation to establish a baseline reference level. All data were compared against CARB, WHO, and OSHA standards (IIT Kanpur Ozone Report).

What 24 Hours of Testing Found

Across the entire 24-hour continuous operation period, ozone concentrations in the sealed chamber remained stable between 1.8 and 2.8 ppb. Both with and without the Pebble running.

No measurable increase in ozone was observed after the device was activated.

The maximum ozone reading at any point during the test was 2.8 ppb, against a CARB limit of 50 ppb and a WHO guideline of 60 ppb. That is roughly 18 times below the CARB threshold.

The IIT Kanpur report also noted a slight downward trend in ozone during device operation, suggesting the ionization process may actually contribute to maintaining or reducing ambient ozone in the chamber rather than raising it.

Why the Sealed Chamber Made This a Strict Test

One cubic foot is an extremely small sealed space. If the Atovio Pebble were generating ozone at any measurable level, that ozone would have nowhere to go. It would accumulate until the 0.01 ppb sensitivity instrument picked it up. There was no ventilation. No air exchange.

The Pebble ran for 24 continuous hours in that space and ozone concentrations never rose above 2.8 ppb. The IIT Kanpur report concludes the device does not generate ozone or secondary pollutants, validating the safety of its ion-based purification process.

The Bottom Line

The IIT Kanpur 24-hour sealed-chamber test provides a clear answer on the ozone question. Maximum ozone observed: 2.8 ppb. CARB limit: 50 ppb. No measurable ozone generation. Fully compliant with CARB, WHO, and US EPA standards. For a device worn close to the face for hours every day, this is the kind of independent scientific confirmation that is worth knowing about. For the PM1, PM2.5, and PM10 removal results from IIT Kanpur's separate particle testing, that data is covered in a dedicated blog.