Have you noticed some people these days wearing necklace devices resembling a small donut or some space-age looking device? Philippine President Rodrigo Duterte wears one, and so does Cebu Governor Gwen Garcia. And more people are starting to use it.
These are actually “personal air purifiers” that also come in the following names as “personal air ionizers”, or “wearable negative ion generators” or “anion purifier necklace”.
We are familiar with home devices marketed as negative ion generators or anion purifiers equipped with HEPA filters. These are even used for cars as negative ion purifiers you can plug into the car charging socket.
The difference in these personal devices are:
- More compact, thus the term “personal”
- Hang around your neck or can be worn on your body
- Run on battery, rechargeable
- Run on electronic mechanism rather than mechanical which would otherwise use physical filtration like HEPA filters
- May emit Ozone
Before you buy one, here’s a closer look on what they do and what you need to take note of.
Negative Ions

The basic science behind these personal devices is that they emit electrically charged ions. These ions carry a negative charge, thus the term “anion” or negative ions.
These negative ions attach themselves to air particles like allergens, viruses, pollution particles, etc. and negatively charge those particles. This causes the particle to become too heavy to remain in the air. The particle will fall out of the air and end up in surfaces around you like walls, tables, chairs, clothes, drapes, etc. rather than make their way towards your nose or mouth and cause allergy or sickness.
So while these devices “reject” the harmful particles, it is very important that basic hygiene, regular disinfection of surfaces, changing clothes, and maintaining physical distancing are still strictly observed.
“In nature, negative ions are generated by processes such as sunlight, lightening, waves from the ocean, and from waterfalls. “Concrete Jungles” minimize the natural production of negative ions by disrupting the delicate electrical balance between the atmosphere and the earth. Ionizer/ionic air purifiers recreate them with electrode pins (“needlepoints”) to electrically produce negative ions. This method produces a density that is many times higher than the negative ion level found at Niagara Falls, the highest natural producer of negative ions and one of the healthiest environments in the world.”
“How Negative Ions Purify the Air” by HeavenFresh
Health Benefits of Negative Ions
Numerous research have supported that exposure to negative ions:
- Help to reduce symptoms of depression for some people
- Have an activating influence on some body systems and cognitive performance
- Promote antimicrobial activity
However more research needs to be done to provide evidence that supports if negative ions:
- Reduce serotonin to help manage anxiety
- Lower blood pressure
- Improve your breathing
Look out for the Ozone
The most important safety factor to look out for in these personal purifiers/ionizers is if they emit ozone. If they do, then the ozone amount, measured in parts per million (ppm) should be within safety standards.
In the Philippines, Ozone safety standards according to the Air Quality Index of the DENR’s Environmental Management Bureau or DENR-EMB, places the Good air quality rating if the ozone level, within an 8-hour period, registers a ppm of between 0.000 and 0.064. It is said to be of Fair levels when it falls between 0.065 and 0.084 ppm.

According to the United States Environmental Protection Agency (EPA) “when inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections. People vary widely in their susceptibility to ozone.” Read more on ozone and its effects including FAQs here.
Check that the personal ionizing/purifying device does not emit ozone, or if it does, is within safety limits.
Apart from the Philippine standards, a widely used standard referred by many air purifying manufactures is the California Air Resource Board (CARB) certification. The California Air Resources Board is under the umbrella of the California Environmental Protection Agency.
The CARB places the ozone safety limit at 0.050 ppm, even stricter than the Philippines DENR-EMB limit.
Is the Device Ozone-Safe?
So before you buy your personal air purifying or ionizing device, check the following:
- Does it emit ozone?
- Is it certified by the California Air Resource Board (CARB) as safe?
- If it emits ozone, how much ozone does it emit?
- Check if the device is listed as CARB certified
- Check if the device is tagged as Potentially Hazardous
What do they use?
It appears Philippine President Duterte and Cebu Governor Garcia are currently using the Japanese-made AirTamer brand, that is also certified by CARB as safe and touts itself as the best in the market. In this photo, Governor Garcia is seen wearing an InvisiClean Mini Ionizer.
Reminders
Again ensure the device you are eyeing does not, or emits only a safe amount of ozone. Since it is an electronic device and a device you can buy online, make sure you look out for:
- The integrity of its battery and charging devices
- Warranty guidelines for repair/replacement
- Customer reviews on the product’s performance and reliability
- Price
Also be reminded that theses devices do not ensure full protection from allergens and viruses like COVID-19. You will still need to ensure basic hygiene, regular disinfection of hands and surfaces, and optimum health are maintained. Physical distancing and wearing of masks in poorly ventilated areas and with numerous persons present, should still be strictly observed.