Some manufacturers claim numerous benefits regarding ionizing air purifier's ability to improve indoor air quality but how does a negative ion air cleaner actually work? Is it really effective at removing gasses and particles from the air as it claims to be? Is this technology safe to use?
What is an Ion Air Purifier?
A negative ion air purifier or an ionizer is a type of air cleaning device that uses a high voltage to shoot negative ions into the air which then clings to the contaminants giving them an electric charge. This causes the newly electrically charged particles to clump together en masse until it becomes heavy enough to simply fall onto a surface making the air feel "fresher".
An electrostatic precipitator is also a type of air cleaning device that utilizes the same techniques as an ionizer but differs in their collection method. An electrostatic precipitator also gives air contaminants an electric charge to make air pollutants susceptible to magnetism but whereas an ionizer tries to make particles cling together to fall on surfaces an electrostatic precipitator will try to have the contaminants attach to oppositely charged plates installed inside their devices.
While electrostatic precipitators tend to perform better than the standard ionizer there exists a number of drawbacks to using ionizing technology as an air cleaner.
Do Ion air purifiers work?
There are two main types of pollutants that affect the quality of your indoor air: gaseous pollutants and particulate pollutants. You can tell how effective an air purifier is based on how effective they are at removing these contaminants from the air.
Gaseous Pollutants- Ionizers are not designed to remove volatile organic compounds (VOCs), odors, and, other gaseous particles suspended in the air. Ionizers may also produce ozone, a harmful gas, as a byproduct when oxygen molecules (O2) are rearranged into ozone (O3) because of the reaction between the electric charges. More details on its ozone generating properties later.
Particulate Pollutants- Ionizing technology when used by itself on an air cleaning device without any other filtration technology for it to work in conjunction with has very limited indoor air cleaning capabilities. Negative ion air purifiers does fulfill its purpose by having electrically charged contaminants suspended in the air clump up together to fall on surfaces.
Since these particles aren't captured in one spot by a filtration device, these fallen particles will accumulate on carpets, fabrics, floors, and furniture creating a very dusty indoor space over time that needs regular cleaning. Whether it be in the process of cleaning or an activity, these dormant contaminants tend to get kicked back into the air through currents cause by movement.
Are ion air purifiers safe?
An important thing to be aware of is that ionizers may create ozone and nitrogen oxide as byproducts when it releases electrically charged negative ions into the air.
Exposure to ozone in high concentrations has been known to cause breathing difficulties and respiratory problems, specially among children and infants. People planning to get ionizers may want to reconsider placing an "air purifier" that might introduce new pollutants to their indoor air.
Ionizers vs. HEPA
If you are looking for an alternative to ionizing air purifiers but without the negative health drawbacks then look no further than your standard HEPA filter. HEPA filtration technology has been in use for a long time and is even a staple on medical facilities as testament to its ability to capture airborne contaminants with a size of 0.3% microns in diameter with 99.97% efficiency (particles that are bigger or lower than 0.3 microns are captures with higher efficiency.) Another added benefit is that HEPA air purifiers tend to not leave rooms dusty because the particles a HEPA filter processes are captured within its fibers preventing it from being recirculated into your indoor air.
Sources:
https://www.sciencedirect.com/science/article/abs/pii/S0021850217303749
https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners
https://www.epa.gov/indoor-air-quality-iaq/what-are-ionizers-and-other-ozone-generating-air-cleaners
https://www.iqair.com/us/blog/air-cleaning-technology/do-air-purifiers-work
https://www.webmd.com/asthma/news/20050404/ionizing-air-cleaners-may-pose-health-hazard