Biomedical Research

COVID-19: Can’t We Just Clean The Air Of It?

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.

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.

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.

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.

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.

Health and Disease

Leptospirosis: What Comes After Floods


Leptospirosis is a zoonotic disease caused by the bacteria genus Leptospira, afflicting both humans and animals alike. The bacteria is spread by animal carriers (such as rodents, cattle, pigs, and more) through their urine, which can get into soil, mud, and water. Humans contract Leptospirosis when they get in contact with the urine of infected animals, or mediums such as food and water contaminated with the urine. The pathogenic bacterium enters the body through the nose, mouth, and open wounds.

Individuals most at risk of contracting the disease are those who work closely with possible carrier animals (like farmers) and those who frequently afflicted rivers or similar bodies of water. Outbreaks are especially common during the aftermath of intense flooding when people are most exposed to contaminated floodwaters.

Leptospirosis Worldwide

While leptospirosis occurs worldwide, it is more prevalent and usually endemic to tropical and humid regions, such as Southeast Asia, Africa, Central, and South America, Australia, and the Caribbean.

Over the years, numerous Leptospirosis outbreaks have been recorded. The recent onslaught of typhoons in the Philippines nearing the end of 2020 saw a small increase in Leptospirosis cases. Despite this increase, the total number of leptospirosis cases in the Philippines for 2020 (1,071) still decreased from 2019’s 3,140. Cases reported in certain regions of the country exceeded the epidemic threshold. There were reports that the National Kidney and Transplant Institutes lacked enough beds for Leptospirosis patients, in addition to the currently limited hospital facilities due to COVID-19 (Montemayor, 2020). Similarly, India reported an increase in Leptospirosis cases last 2020 compared to their 2019 record, counting 153 from their previous 83 (Suresh, 2020).

Because the majority of leptospirosis cases occur in developing countries, reports and details about these cases are often under-reported. However, there are still efforts to accurately determine global incidence rates and statistics about leptospirosis.

Symptoms, Signs, and Treatments

The incubation period of leptospirosis lasts 2-30 days, while signs and symptoms (illness) may be felt within five days to two weeks after exposure. However, some patients may be asymptomatic.

Some symptoms include high fever, chills, jaundice, head and muscle aches, abdominal pain, diarrhea, vomiting, and skin rashes. Milder cases of leptospirosis may be confused with the common flu. The illness may occur in two phases: (1) a case of fever, chills, body aches, vomiting, and diarrhea, after which the patient may feel better, and the second (2), which manifests more severely, triggering possible kidney, liver failure, or meningitis.

Doctors prescribe antibiotics such as doxycycline and penicillin to treat leptospirosis. However, the best way to prevent leptospirosis is to avoid contaminated waters. From a public health perspective, preventing leptospirosis outbreaks also means promoting access to clean water and better community sanitation and hygiene.

Conclusion: Current Issues and Possible Resolutions
According to Trott et al.’s study (2018), most Leptospira strains remain susceptible to doxycycline and other antimicrobial agents used for acute leptospirosis. In Chakraborty et al.’s research (2010), they were able to show that Leptospira strains were resistant to amphotericin B, 5-fluorouracil, fosfomycin, trimethoprim, sulfamethoxazole, neomycin, and vancomycin but susceptible to ampicillin, cefotaxime, ciprofloxacin, norfloxacin, doxycycline, erythromycin, and streptomycin.

Even with the current effectiveness of certain antimicrobial agents (such as doxycycline) for leptospirosis, antibiotic resistance remains a problem for the future of bacterial diseases. The misuse of these antibiotics can affect the future of leptospirosis treatment.

The prevalence of leptospirosis globally also remains a problem, given the increase in population and urban slums. Its manifestation poses more questions for the general state of public health, especially for developing countries. While leptospirosis is a very treatable disease, the overall prevention of it can be done through better identification of risk controls and addressing those. Policymakers can focus on imposing better occupational hygiene standards and protocols, water drainage, educational campaigns, national sanitation services, and vector control. National and local governments alike should strengthen sanitation measures.

With the inevitable coming of stronger typhoons and hurricanes because of climate change, flooding is inescapable as well. All health departments, especially for countries that are most affected by these natural disasters, should acknowledge the possible outbreaks and thus prepare accordingly.

As it is, developing countries remain the most vulnerable to leptospirosis outbreaks. Some may even argue that health issues of developing countries, not just leptospirosis, are largely brought about by deeply-rooted colonialism and imperialism. Notwithstanding, without the resources and financial capacity most advanced countries have, implementing effective sanitation measures— and thus, solving leptospirosis outbreaks, remains a distant dream.

Elmira Decena, Youth Medical Journal 2021


Montemayor, M. T. (2020). DOH notes drop on leptospirosis cases. Philippine News Agency Retrieved from:

CDC. (2019). Leptospirosis. Center for Disease Control and Prevention. Retrieved from:

Suresh, M. (2020). Dengue, leptospirosis cases. The New Indian Express. Retrieved from:

Trott, D. J., Abraham, S., & Adler, B. (2018). Antimicrobial Resistance in Leptospira, Brucella, and Other Rarely Investigated Veterinary and Zoonotic Pathogens. Microbiology Spectrum, 6(4). doi:10.1128/microbiolspec.arba-0029-2017

Chakraborty, A., Miyahara, S., Villanueva, S. Y. A. M., Gloriani, N. G., & Yoshida, S. -i. (2010). In Vitro Sensitivity and Resistance of 46 Leptospira Strains Isolated from Rats in the Philippines to 14 Antimicrobial Agents. Antimicrobial Agents and Chemotherapy, 54(12), 5403–5405. doi:10.1128/aac.00973-10