By Elmira Decena
Published 5:18 PM EST, Tues March 16, 2021
Globally, there have been great advances in handling the COVID-19 pandemic. Countries like the UK, United States, and Israel have been rolling out COVID-19 vaccines to its population. Some others, like New Zealand, Taiwan, and Singapore, introduced rigorous contact tracing and strict physical distancing rules right from the start.
A year into the global pandemic, more public spaces are re-opening, even when the public remains vulnerable to COVID-19 transmissions. While vaccination and herd immunity remains to be the best approach to handle COVID-19, there are fad products booming in the market, which often promote themselves as the virus end-all-be-all product. Take, for example, personal air ionizing purifiers. Some market these purifiers as essentials for going out in the new normal, claiming that they’re effective against COVID-19 aerosol transmission.
But exactly how accurate are these marketing schemes and strategies?
The Negative Ion Air Ioniser/Purifier
Should anyone try searching for negative ion air purifiers online, they would find a host of products claiming to remove dust, smoke, viruses, and other harmful particles from the air, through the use of negative ions. The principle of the ioniser is simple. Air pollutants are often positively charged. The air ioniser releases negatively charged ions into the air, which are then attracted to the positively-charged air pollutants. When the pollutants and the released negative ions form bonds, they become significantly heavier than they are individually. With their increased weight, they either accumulate on the ground because of gravity or on an electrostatic collection plate, which then clears the air of their presence.
How effective are ionizers in air purification?
Negative ionization has seen numerous uses in air purification and air quality maintenance. A 2017 study (Shiue et al.) showed that negative ions were able to remove pollutants of various sizes, including particulate matter (PM2.5), from the air. This is also supported in a later review, Jiang et al. (2018), which confirmed the ability of negative ions in cleaning air of particulate matter with diameters less than 10 micrometers, PM10. Additionally, negative ionization has also been used to clean the air of smoke-related particulate matter (Černecký et al., 2015).
In 2015, Hagbom et al. researched an air ionizer device on market, which claimed to remove airborne and aerosol particles from the air, including airborne virus strains calicivirus, rotavirus and influenza. Similarly, negatively-charged air ions were able to prevent the transmission of Acinetobacter infection, hypothetically pushing away the airborne bacteria as found in Sheperd et al., (2010)’s research. A study by Grinshpun et al. (2005) evaluated portable air ionizers and found that they were effective in reducing aerosol exposure.
Does it work against COVID-19?
According to the World Health Organization, COVID-19 is spread through aerosol droplets. Past research shows that air purification methods based on ionization, were effective to certain extent at clearing the air of airborne particles. This implies that similar effects might be applicable to COVID-19 as well.
OK, so do negative ions have any health benefits at all?
There are limited studies regarding the actual health benefits of negative ions. Positive physical effects such as improved lung function and heart rate variability observed are mostly the result of the removal of particulate matter and not the actual ions (Liu et al., 2020). Antimicrobial and antiviral effects are also due to the removal of these particles in air and not their deactivation (Hagbom et al., 2015).
Negative ion air purifiers are indeed functional in cleaning the air of pollutants and particulate matter, including aerosol and airborne microbes and viruses. They may be useful for individuals who are often located in areas with high air pollution or are heavily allergic. These purifiers do not kill or destroy bacterial and viral organisms. Furthermore, such claims of directly-related health benefits from negative ions are not backed by research. So while ionizers may have some possible success at purifying the air, it is not the magical cure for COVID-19, nor is it to be considered an alternative safety measure. The best protection from COVID-19 continues to be masks, social distancing, and frequent hand-washing, at least for the near future.
Elmira Decena, Youth Medical Journal 2021
Shiue, A., Hu, S.C. and Tu, M.L. (2011). Particles Removal by Negative ionic Air Purifier in Cleanroom. Aerosol Air Qual. Res. 11: 179-186. https://doi.org/10.4209/aaqr.2010.06.0048
Jiang, S. Y., Ma, A., & Ramachandran, S. (2018). Negative Air Ions and Their Effects on Human Health and Air Quality Improvement. International journal of molecular sciences, 19(10), 2966. https://doi.org/10.3390/ijms19102966
Černecký, J., Valentová, K., Pivarčiová, E., & Božek, P. (2015). Ionization Impact on the Air Cleaning Efficiency in the Interior. Measurement Science Review, 15(4), 156–166. doi:10.1515/msr-2015-0023
Hagbom, M., Nordgren, J., Nybom, R., Hedlund, K. O., Wigzell, H., & Svensson, L. (2015). Ionizing air affects influenza virus infectivity and prevents airborne-transmission. Scientific reports, 5, 11431. https://doi.org/10.1038/srep11431
Grinshpun, S. A., Mainelis, G., Trunov, M., Adhikari, A., Reponen, T., & Willeke, K. (2005). Evaluation of ionic air purifiers for reducing aerosol exposure in confined indoor spaces. Indoor air, 15(4), 235–245. https://doi.org/10.1111/j.1600-0668.2005.00364.x
Liu, S., Huang, Q., Wu, Y., Song, Y., Dong, W., Chu, M., Yang, D., Zhang, X., Zhang, J., Chen, C., Zhao, B., Shen, H., Guo, X., & Deng, F. (2020). Metabolic linkages between indoor negative air ions, particulate matter and cardiorespiratory function: A randomized, double-blind crossover study among children. Environment international, 138, 105663. https://doi.org/10.1016/j.envint.2020.105663