This article discusses the potential negative effects negative ion air purifiers have on human health. Also, the positive effects are elaborated, and finally a comparison between the pros and cons is done in order to assess whether a negative ion air purifier is worth investing in.
Can negative ion air purifiers be harmful?
Yes, negative ion air purifiers can have negative implications to human health. Air purifiers are devices which, as the name suggests, clean the ambient indoor air.
There are mainly two types of air purifiers – ones use filters and pull in the indoor air, which causes the pollutants to get filtered out, thereby cleaning the air.
The other type of air purifiers, which is the main subject of this article, are the air ionisers. These devices generate ions, in this case anions (i.e., negatively charged ions), which do so by using a mechanism called corona charging.
These anions interact with pollutants that have a charge. When these combine, the pollutant species become heavy and get removed from the air by settling on the ground.
Side effects of anionic air purifiers
Anionic air purifiers, although used widely nowadays, as personal air purifying necklaces, indoor air purifiers, and other similar appliances, do have certain side effects attached with them during their working. This includes:
- Low efficiency
- Production of ozone
- Can attract pollutants on the body
- Can generate more dust
Let us discuss these in more detail.
Conventional air purifiers are known for their high efficiency rate of removing pollutants from the ambient air. However, the same cannot be said for anionic air ionising purifier.
In an experiment carried out by Shi et al, air purifier necklaces that use anions as their purifying mechanism were used from different brands in a small stainless steel chamber.
It was found that the particles had a highly variable particle removal rate, but did not perform efficiently. Some of the devices had discharged at a relatively shorter amount of time.
Production of ozone
Anionic air purifiers work by generating ions at the rate of thousands per minute. They do so by using a mechanism called corona charging, in which oxygen molecules can also get broken down, which in turn react with each other to form ozone.
Ozone is a highly reactive gaseous molecule which is naturally present in the upper layers of the atmosphere, where it absorbs the sun’s damaging ultraviolet radiation.
When present in the lower levels of the atmosphere, however, it acts as a pollutant, and can have serious adverse effects on human health, which also includes afflictions related to the cardiovascular and respiratory systems.
Ozone acts as an irritant, due to its pungent odor. It can cause wheezing, irritation in the nose and throat, runny nose, watery eyes, difficulty in breathing, and so on.
Additionally, ozone can also worsen the condition of people who are suffering from diseases such as asthma, emphysema, and bronchitis.
Can attract pollutants on the body
Anionic air purifiers work by releasing ions in the vicinity of the user. These ions can also get stuck to the skin, particularly in the face and neck region.
In turn, these ions can attract pollutants towards the user itself, and can cause deposition of pollutants on the skin of the user. This can cause adverse effects on the skin, depending on the nature of the pollutant species.
Certain toxic species, which are heavy metal pollutants like lead, can be attracted towards the skin, and can have serious implications on the health of the user.
Additionally, in case if the air contains Volatile Organic Compounds, or simply VOCs, the ozone generated from the device as a byproduct can react with the VOCs in order to give rise to secondary organic aerosols (SOAs).
These SOAs do not have any implications on human health. However, they reduce the efficiency of the anionic air purifiers, as they reduce the particle removal performance.
Can generate more house dust
Unlike the air purifiers with HEPA filters, air ionisers do not help with dust present in the house. On the contrary, they would contribute even more to the dust generated indoors.
Air ionisers interact with the charged pollutant particles by sticking to them, causing them to become too heavy to stay suspended in the ambient air.
This would in turn cause deposition of dust on surfaces such as carpets, tables, etc., which in turn would exacerbate the effect of dust already present indoors.
However, it would be ideal to pair it with an air purifier containing a HEPA filter, as it would increase the efficiency with which the indoor air gets cleaned.
Do anionic air purifiers offer any advantage?
Anionic air purifiers also have certain advantages, which include:
- Helps in relieving symptoms of allergies
- Gets rid of odors
- Can efficiently remove ultrafine particulate matter (UF).
We shall discuss them in brief.
Helps in relieving symptoms of allergies
Studies have shown that air ionisers are effective in getting rid of allergens, which include pollen, spores from mold, animal dander, dust, and so on.
These allergens usually have a charged surface, due to which they can attract the ions generated by the air ionising necklace.
This, in turn, causes the particles to get too heavy, due to which they cannot stay suspended in the air for a while, which in turn causes them to sediment.
This helps to reduce the number of allergens which can get inhaled, due to which an allergic response can get triggered in people.
Gets rid of odors
Air ionisers interact with odor causing molecules as well. Odor is caused when a particular pollutant interacts with the sensory neurons present in the nose lining.
This is done by different bonding sites. Hence, different substances have a distinct odor. However, these ions interact and bind to the bonding sites of the odor causing pollutants.
This, in turn, renders the pollutants ineffective, due to which the odor cannot be picked up by the nose. Therefore, air ionising necklaces are useful especially when one is passing through polluted areas such as open dumps or sewages, traffic, and so on.
Can efficiently remove ultrafine particulate matter (UF)
Ultrafine particles (UF) are a class of particulate matter (PM), which are less than 1 micron in terms of aerodynamic diameter. These are generated from various sources, such as traffic, industrial emissions, combustion, cigarette smoking, etc.
There are many studies that have established a correlation between exposure to UF and reported cases of illnesses related to pulmonary or cardiovascular systems, cancers, and in some cases, premature deaths.
This is primarily because these particles can easily penetrate all the way through the respiratory passage, and end up in the deep recesses of the alveoli, the site where air exchange between the lungs and blood takes place.
However, ions generated by the air purifier can efficiently pick out these UF particles and in a way similar to that for allergens, remove them from the ambient air.
Should you invest in an anionic air purifier?
No, you should not invest in an anionic air purifier. Even though it has some advantages, the side effects outweigh those, particularly the generation of ozone alone.
In some places, such as California in the United States, air purifiers that produce ozone are outright banned for manufacture and sale in the entire state.
Therefore, for people living in these areas or visiting these areas, it would be useless to use or buy an anionic air purifier.
Other FAQs about Air Purifiers and Filters that you may be interested in.
Anionic air purifiers, also known as negative ion air purifiers, have certain side effects on the health of the user. These side effects include low efficiency, dust generation, attracting pollutants to the body of the user, and lastly, generation of harmful ozone gas.
We then take into consideration the advantages the anionic air purifier offers to its user. However, the side effects far outweigh the benefits one may expect to draw from these devices.
What are the alternatives to buying a negative ion air purifier?
It would be better to invest in an air purifier which utilises HEPA filters as its method of purifying the air. These filters have an efficiency of more than 99% for particles equal to or more than 0.3 microns in aerodynamic diameter.
These filters can also contain additional components, which include a germicidal UV light chamber, which helps to neutralise microorganisms entrapped in the filter, and activated carbon filters, which efficiently absorb gases into their filter media.
Are air purifying necklaces worth it? If not, what are the alternatives?
No, air purifying necklaces are not worth it. Firstly, air purifier necklaces need to be charged externally in order for them to function. However, the charge does not last for long, as some air purifier necklaces get discharged by 36 hours itself.
Furthermore, in an experiment carried out by Shi et al, air purifier necklaces from different brands were used in a small stainless steel chamber. It was found that air purifier necklaces have a high variability in their efficiency, but values are typically low.
Lastly, even these devices produce ozone, which can trigger asthma attacks in people along with other allergic reactions.
Some better alternatives to this are:
Avoid places with traffic congestion
As it is evident, traffic-related pollution is a major contributor to many health issues. So, it is best practice to avoid areas which have high traffic congestion or are prone to it. If it is convenient, one should travel in off-peak hours when there’s no traffic.
On the other hand, one can choose an alternate way of transit via a route which doesn’t have much traffic and is economical as well.
Check pollution levels before leaving
If you live in an urban area, it would be a good idea to check the pollution levels before leaving, so that you can plan your trip accordingly.
There are many government and non-government organisations that are responsible for tracking the concentration of major air pollutants in the city and provide real-time data for the public.
Clean your indoor air
An average American spends 93% of their total life indoors. 87% of their life is inside buildings, then another 6% of their life is in automobiles.
Over the last several years, a significant amount of scientific reports provide evidence of air pollution inside buildings and homes, referred to as indoor air pollution (IAP), which is more serious than outdoor air pollution, even in industrialised cities and metropolitan areas.
Thus, a person has a higher health risk from indoor air pollution than from outdoor air pollution. The best way to deal with IAP is by the following methods:
- Improving ventilation of the house.
- Using an air dehumidifier to reduce the relative humidity of the home.
- Avoid smoking or combustion of fuels inside the house, as these processes adversely affect the indoor air quality.
- You can invest in a HEPA air purifier.
Air purifiers with HEPA (High-Efficiency Particulate Air) filters are best suited for indoor purposes. The presence of an activated charcoal filter and a UV light further increases the efficiency of the filters.
- Shanshan Shi, Shihao Zhu, Eon S. Lee, Bin Zhao & Yifang Zhu (2016) Performance of wearable ionization air cleaners: Ozone emission and particle removal, Aerosol Science and Technology, 50:3, 211-221, DOI: 10.1080/02786826.2016.1139045
- Norris, G., YoungPong, S. N., Koenig, J. Q., Larson, T. V., Sheppard, L., and Stout, J. W. (1999). An Association Between Fine Particles and Asthma Emergency Department Visits for Children in Seattle. Environ. Health. Persp., 107:489–493.
- Jiang SY, Ma A, Ramachandran S. Negative Air Ions and Their Effects on Human Health and Air Quality Improvement. Int J Mol Sci. 2018;19(10):2966. Published 2018 Sep 28. doi:10.3390/ijms19102966
- Gabbay J, Bergerson O, Levi N, Brenner S, Eli I. Effect of ionization on microbial air pollution in the dental clinic. Environ Res. 1990 Jun;52(1):99-106. doi: 10.1016/s0013-9351(05)80154-9. PMID: 2351131.
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